I mean I’d accept it as being a sex-negative insult that implies people who have a lot of sex deserve to be insulted but for it to be anti-bisexual assumes all bisexual people have a lot of sex which is an anti-bisexual position to begin with.

so the context is that a trans woman called a cis bi white man this (because he's been obsessively stalking her) and he's now crying that it's a biphobic slur