I am not an expert on this, but I think the kind of person I have in mind would not bother to look for willing BDSM victims. From their point of view, there are humans all around, and their consent is absolutely irrelevant, so they would optimize for some other criteria instead.

This feels to me like worrying about a vegetarian who eats "soy meat" because it exposes their unconscious meat-eating desire, while there are real carnivores out there.

specify which kind of people you want to remove from the community

I am not even sure if "removing a kind of people" is the correct approach. (Fictional evidence says no.) My best guess at this moment would be to create a community where people are more open to each other, so when some person harms another person, they are easily detected, especially if they have a pattern. Which also has a possible problem with false reporting; which maybe also could be solved by noticing patterns.

Speaking about society in general, we have an experience that sociopaths are likely to gain power in different kinds of organizations. It would be naive to expect that rationalist communities would be somehow immune to this; especially if we start "winning" in the real world. Sociopaths have an additional natural advantage that they have more experience dealing with neurotypicals, than neurotypicals have with dealing with sociopaths.

I think someone should at least try to solve this problem, instead of pretending it doesn't exist or couldn't happen to us. Because it's just a question of time.