I 100% see an IRL couple in that situation as gay, and see m/m ships with a trans character as gay, cause yeah, it's two guys. Anyone who doesn't feel the same can fuck right off. At the same time though, PIV has heavy social connotations around heterosexuality and carries a lot of baggage. For trans people too, not just for transphobes. When it comes to a made up sexual fantasy, I don't see it as transphobic when readers don't want to imagine PIV.
Re: Secrets you don't want to make...
I 100% see an IRL couple in that situation as gay, and see m/m ships with a trans character as gay, cause yeah, it's two guys. Anyone who doesn't feel the same can fuck right off. At the same time though, PIV has heavy social connotations around heterosexuality and carries a lot of baggage. For trans people too, not just for transphobes. When it comes to a made up sexual fantasy, I don't see it as transphobic when readers don't want to imagine PIV.