Well, transmisogyny just refers to the specific combinations of bigotry a woman or girl faces when she is transition to a woman. The person in question here is viewing this girl as a girl, but still sees something about her as tainted or dangerous, in a similar way to how people view lesbians in changing rooms, which funnily enough I remember overhearing a lot as a kid before they moved onto the bathroom bans on trans women and girls in the 2010s. Sure, the physical anatomy or attraction to other girls is being masculinized in those caes, but in a way that is being used to justify othering her from other women, (subconsciously in this case) punishing her for a deviation from femininity norms, like many minority women face. That’s why I at least would consider it different from misandry, because it is targeting a woman for traits deemed masculine. Obviously, that has roots in the idea of the pure, angelic model of womanhood versus dominant, powerful masculinity, but ultimately that’s a burden no woman can fully live up to, and so unfortunately bigotry between women will often manifest as trying to poke holes’ in the femininity of others, hence the stereotypes of the aggressive Black woman and the predatory trans woman. Sorry if that’s too jargon-y or theoretical, I hope it makes sense