If the idea is that several people are being given magic to shape the world around them, then that's definitely something I could see Discord (either Equestria's Discord or the EqG version, who is still a spirit of chaos who was restrained but was freed when Equestrian magic started seeping in) being the one responsible (perhaps he's aware but still sealed and thus can't do anything himself, thus he sloughs off bits of his power and lets them grow inside of others to cause chaos and eventually free himself). After all, a bunch of selfish reality-warpers all trying to twist the world to their whims would create chaos in abundance. In that case, he actually probably wouldn't support the player, because even if they go full Bimbo Magic, they're still restrained enough to cause their changes gradually enough that they become innocuous and unnoticed, and thus aren't really causing "chaos" so much as just creating a "new normal." It's not chaos if everybody just nods their heads and accepts it, after all.
In that scenario, the Proprietor of the Violet Room might be a being who is trying to keep Discord locked away (and is perhaps the one who did it in the first place. Ancient human Starswirl? Celestia and Luna's distant but identical ancestors?), but is unable to remove or restrain Discord's power in its human hosts (possibly due to being just a spirit these days), and can't just convince them not to use it (perhaps because Discord made sure his powers would seek out hosts who would be driven to use it, hosts who have the desire to shape the world around them and the willingness to do so even at others' expense). Thus, they instead try to get the player to be their agent to stop the other hosts - perhaps the player has a choice in using the power for their own gain (via bimbofying girls) or not because the Proprietor managed to snag one of the pieces of Discord's power, but was forced to immediately stick it in the closest host they could find to keep it from going free, thus the player wasn't selected specifically by either party (though the Proprietor might lie and try to pretend he was) and can choose how they use their power.
So in that scenario the Proprietor of the Violet Room would actually be counseling responsibility and restraint, or failing that will present themselves as the ones focusing the power to cause the changes, which is a lie meant to keep it happening gradually enough that it creates the scenario of a "new normal," which will at least ensure that Discord doesn't go free. Meanwhile, the little sliver of Discord's power within them might have a mind of its own and will tell them they don't need the Proprietor and should just let loose, bend reality over a table and f*ck it senseless (along with every girl at CHS that catches the player's eye, of course). This would be a bit of a subversion of expectations for Persona players; they're used to always having someone who never lies to them and is always helpful in the form of the Velvet Room's inhabitants. That's actually a standout from the normal Shin Megami Tensei franchise and most of its other spinoffs, so it could be an interesting thing to play with. Especially if a player goes the "no/minimal bimbo" route and thus never learns that they're lying to them, then goes another route where they do find it out.
But in this scenario, I think there would need to be two matrices to decide an ending: both how much you use the bimbo magic and how many "good" endings you get to Social Links (that is, whether they succeed in their personal goals or fail, be that failure be because the player couldn't get the stats to help them enough - you might want to give some indication of what stats you need to have to accomplish something - or because they bimbofied them in such a way that they no longer even care about them (making Twilight a party girl who doesn't even care about school, for example).
So a low bimbo, low good ending ending would be the "worst" end, "The Daily Grind," where your lack of commitment leads you to just drift through a normal life, a job that isn't terrible but not that great, a couple of friends and maybe a lover, but always with the knowledge that you could have had more (though maybe if you got at least one Good End you have a lover who makes it all better, so if not ecstatic with how you're life turned out, you still think it was all worth it). The low bimbo, high good ending would be "A Charmed Life," where your willingness to change yourself rather than selfishly demand the world change around you (by putting in the work to raise your stats and putting yourself out there to help others) leads you to living a happy life with a successful career you enjoy and a large circle of friends (and/or lovers, if we're going with the Persona thing where you can just romance everyone without any real consequence). The high bimbo, low good end is "My Private Heaven," where you've changed people and the world to suit your own ends with no thought for anyone but yourself. But just because you're selfish, does that mean the world you've created is wrong, when everyone's happy and gets along? The high bimbo, high good end is "The New Normal," where through a combination of diligence, magic, altruism and selfishness you've done what every great man tries to do: create a better world. You've helped people attain the things they wanted, and kept their own natures intact; aren't they still themselves, then, pursuing those same dreams? And if everyone's got the bodies of porn stars and are very sexually liberated, well, what's really wrong with that in the end? After all, don't people talk about great men shaping the world? What does it matter if you do it a bit more literally? You certainly put the work in, after all.
The problem is that this kind of requires writing 4 outcomes to every character's story, so for example using Twilight we get:
Low Bimbo, Bad End - Unwilling to bimbofy Twilight (at least past level 2) and unable to convince her to change her self-destructive habits, you end up watching Twilight spiral into either a collapse from exhaustion or a full-on breakdown. Either way, she ends up hospitalized and misses the deadline for her program. You visit her, and at first she's happy to see you (especially if you initiated a romance with her), but soon breaks down crying, convinced she's pushed the rest of her friends away so much that she's lost them and the chance to get into the program, as they haven't come to visit yet. If that seems too depressing, you can have her friends come in at that moment, concerned for her and with assurances that they still care.
Low Bimbo, Good End - If the player uses their high stats to convince Twilight to slow down and accept help from others, she reconnects with her friends and manages to stay healthy and sane and pass her application with flying colors, and her friends hold a party to celebrate. Twilight has learned that no amount of scholastic success is worth shunning all the people who make your life special for.
High Bimbo, Bad End - You've bimbofied Twilight and used your influence over her to convince her to stop caring about the program - and studying entirely. In fact, she doesn't care about anything but having fun with her stud (you), blowing off school and friends alike to be a total party girl.
High Bimbo, Good End - You've bimbofied Twilight, but kept her mind intact and used your influence over her to convince her that her friends and happiness are more important than getting into the program, but still encouraged her to go for it. With support from her friends, far less stress, and still retaining at least most of her prodigious intellect (possibly requiring a lot of studying with a high Int player), Twilight manages to get into the program and throws a big party, later leading to a much smaller one that's just the two of you. Twilight is still the same amazingly intelligent (and often dorky) young woman who's almost sure to succeed at whatever life she chooses and a circle of great friends that she loves dearly - but now she's also a total bombshell with a sky-high libido.