that's a statement close to accusing such people of being sort of perverts undercover

Not being an undercover pervert may be true of you, but I've seen plenty of examples of people asking a very similar question on asexuality forums: Can I be ace if I have a fetish? Can I be ace if I have a kink? (usually BDSM.) Very often, people with these questions are told that yes, because they don't like sex, they are in fact asexual. Sex seems to be the only thing that counts as sexuality for the asexual community. But explain... BDSM, furry, autogynephilia, etc, and how those things have nothing to do with sexuality? (It looks like to me in atypical sexuality, roughly 10% across the board are only into whatever their atypicality is.)

I've made a few posts at these places pointing out how the concept of "asexual" for someone who has atypical sexuality isn't a particularly good way to put it. In one instance, I was straight-up told not to say this sort of thing out loud, because otherwise, they wouldn't be able to sneak kinks and fetishes in through the backdoor of LGBTQ+ via the "A".

I have zero problem with these sorts of people doing their own social rights movement on their own. Take furries for instance. Furries are weird. The good ones know they're weird and I love 'em for it. But furry apologists, don't try and tell me that this isn't a sexual thing for you. Because if you build up some sort of rights movement on that it's not having anything to do with sexuality, then someone will pull back the curtain at some point, and the whole enterprise will go poof. (Looking at you too, AGP.) I'll probably be the one doing it. But like what would that rights movement entail? The right to fursuit in public? I'm against that, on account of believing sexuality should be done in private. The right to not be fired from your job because you do furry stuff on the weekend? I'm for that.

Implicit in all this is that if you're attracted to anthropomorphic animals, then it is detracting away from your interest in sex with adult humans--which is how the ace crowd defines asexuality. Per their definition, anyone with any atypical interest in the slightest must be on the spectrum. Per the definition of asexuality provided by the asexual community, any person with even a slight atypical interest is on the asexual spectrum. Logical outcome.

So, this is essentially something the asexual community asexual catch-all bucket is faced with. Y'all need to sort that out. Gatekeeping can be a good thing.

Edit: The insistence that asexuality has only to do with sex and not atypical sexuality, is either due to ignorance, or some active desire to omit atypical sexuality from the definition of "sexual." For purposes of backdooring K for kink and F for fetish into LGBTQ+, my guess.