It’s not so much being “run” by tankies, as it is being developed. So that should be respected. And it’s being built in a way that seems in line with anarchist principles, which allows for federation. If there’s a problem another instance could easily be created. If you don’t like it, take direct action and spin up a server.
Right now I think this instance is fine. It’s much better than a place like Reddit which is full of libs, or other sites full of nazis - and all run for profit with targeted advertising and tracking.
I also think it’s good to at least engage with each other. Even if you consider yourself an anarchist, it’s still good to read theory from other schools of thought, and at least take on board some of the tankie criticisms. You might also change some minds along the way.
Anyway, there’s a lot to be done in unionizing our workplaces, building mutual aid networks, spreading propaganda, building software, etc. etc. So this topic is probably a bit of a dead end.