Part of the problem may be that the people defending this are simply unable to put "trans" and "fetish" together in their minds.
To some extent I think women can be more prone to this, because if you lack imagination, which is common, and haven't any real experience of having that kind of sexual proclivity or the potential for it, it seems very alien. I've talked to women who simply can't get their head around AGP - it just seems like a crazy thing someone made up.
The other problem is that they have associated idea like this with things like seeing gay men as risks to kids. They have accepted totally that this was a bigoted idea. It goes beyond that though - quite a lot of women who think this way won't even allow themselves to recognize some of the stuff that goes on in the Peter Thatchall end of the gay community, particularly some of the attitudes around sex with teenagers. It's too close to the possibility that teens might be at risk with those individuals, and that is filed under "things you can't think."
Thee are a lot of thought terminating ideas among progressives, and it seems to really impede thinking about things in a realistic way, much less deeply.