I mean, the loudest openly homophobic politicians have a tendency to be caught sucking dick in a parking lot so it's not that weird I would say. Something about living in a culture where it's frowned upon, being ashamed of oneself and taking this shame and frustration out on others. I'm too lazy to look up any data to verify this, but I'd bet that those people are not from countries where being gay isn't stigmatized. Most sane people simply skip those scenes, and pursue scenes of their interest. They also don't waste their time in forum threads about games which they're not the intended userbase.
Although, I will say that when it comes to furry games there seems to be a disproportional amount of gay-only or trans/futa-only games compared to straight, but maybe there's just more LGBT people in the furry community compared to other demographics.
Anyways, the best porn games will have optional content that would satisfy any sexual orientation anyways. Would be stupid to artificially limit the userbase/cutting off different demographics, at least from an economic PoV.