I'm glad the game resonated with you so well on a personal level.
In regards to the fatphobia, this was an intentional exploration of a facet of L's character and not a reflection of my actual views on fat people. The postmortem goes deeper into this:
This was pulling on a common thread for transmascs that being skinny is an inherent trait to passing; the rassaku.net guide being the most obvious signpost of this [...] L is a skinny twink who benefits from societal fatphobia. That's a key part of his character and his relation to being trans. To remove that would be pretending a huge issue within online transmasculine spaces does not exist.
Why is fatphobia one that bubbles to the surface against everything else L thinks? Because it's a conversation that's starting to get louder, and one in current Tumblr contention, and the person he deems the villain in this story is fat. He refuses to confront it fully, knowing subconsciously how much this line benefits him, with it constantly staring him down with the knowing that he shouldn't think it. At the very least, he decides to be polite enough to never say it to someone's face.
It's been a point of contention with its inclusion, but I sincerely believe that you cannot have a discussion of the less-than-savoury aspects of the transmasculine experience without including it. Given who L is and the benefits he gets from not uprooting those beliefs, even if he knows they are harmful, it would be remiss for me to not bring light to it as a core part of his (and many others') experience.