No offense, but like others have stated, this game demo was released with the otome and josei jams that have been going on in the past two/three months.
This years bl/yaoi jam is still ongoing till august (btw i can recommend you actually look into all the entries of the past years bc yaoi/bl. soo many good ones, if you want recs. Just say it. On this site here at least yaoi/BL definitely are not rare! I'd even argue it's less common to find romance w/ NSFW written with fem characters that is not h3ntai. Plus of all queer groups gay men are the most represented, popular in all forms of media, just saying. GL and others don't even compare. Why? Internalized Misogyny.).
Also there are a lot of great games with customizable protagonists/pronouns (often with tags like Amare). Check them out first, before coming to games that are not fitting your criteria of game. Like you knew that with the tags so why look in Otome and Josei?
And also the dev even wrote that they might include other gender expressions for the MC in the future, soo..
But I think regardless, there's no need for every game to have customizable protagonists, esp. if that character is one of the genders that is significantly less represented. Idk you don't need to force yourself to play a game with a fem protagonist bc of your dysphoria but everyone else why shouldn't they, even if they aren't women themselves, be able to play such a game. We women have do it all the time, don't we? I don't see anyone under a BL complaining about not having a fem protagonist (which is good!), so why the other way around? Btw I disagree with one of the comments above: that's not heterophobia but more so (internalized) misogyny.
Ofc customizing protagonists is awesome, neccessary and should be a goal for inclusivity but yeah you can give a feedback that doesn't use words like "I hated" bc like someone else said, there's no need to put pressure on the dev like this. Esp. if you come around and expect it here but not vice versa. Other than that, if it's constructive why shouldn't you be able to be entitled to your opinion.
Oh also there's the Queer Games bundle sale still going on!