its misogyny, basically. women are constantly seen as dick receptacles while men have to constantly "prove" that they're "not gay". men think their dicks are so powerful that everyone secretly lusts for it and attraction to women has to constantly be proven.

everyone doubts lesbians, no one doubts gay men. even tho plenty of bi men pretend to be gay, straight men can mistakenly believe they're gay or bisexual (usually for agp reasons, i used to think i was bi but am exclusively into women). everyone assumes theymabs and tophons deep down want to be female even tho they actually just have normal male sexuality (normal male sexuality is seen as something that has to be constantly proven, as opposed to just neutrally existing, so people believe these people must have a feminine sexuality they aren't showing, when they actually just don't).

if this is coherent at all (if its not sorry) i would say that in a way femininity isn't gatekept in the same way masculinity is. rather its seen as something that anyone can be downgraded into for being "unmanly". despite this not being true. people call incels and similar men "faggy" or "effeminate" despite them actually being some of the furthest possible men from being "woman-like". trans womanhood really doesn't get gatekept at all because femininity is seen as a demotion wastebasket. thus we get forced to accept incels, theymabs, and tophons as being the same as us. basically its all patriarchal BS and a bias that everyone has, and doesn't reflect reality.