I know that I'm always really afraid of streamers I'm watching making some really edgy jokes, myself (like the sort of stuff you'd see on anime imageboards...), but the terf situation, although something that would absolutely devastate me if it happened, isn't really something that'd happen...... because most of the folks I watch are trans to begin with, pff. I do know it's not very helpful saying "watching trans folks would probably make you feel secure about that!!", but y'know...... trans people are some of the best streamers, that's a fact.
If you know it's bad brain stuff with the streams you watch, though, then hopefully such anxieties can simply be overcome!! And if the communities really are small ("small" to me implies sub-10 viewers, dunno if that's accurate), then, if nothing else, interacting with the streamer and forming a positive acquaintanceship in the process would, hopefully, help make them value your own input and such, if a fucking terf ever did show up.
Terf shows up and you, rightly, go "this fucking sucks" and the streamer concurs, destruction unfolds. That sort scenario isn't that unlikely, I think!! I don't know what sorta folks you regularly watch, but hopefully they'd orbital cannon fuckers like that.