That may or may have been warranted but these days "some arguably racist stuff" is a too vague description to be meaningful to act on, or pass judgement by on its own.
Do you have the link to the relevant reddit-thread for better context?
https://www.reddit.com/r/StableDiffusion/comments/103upr6/co...
If it was just one of those examples, sure. But there are multiple things that are 'arguably racist' combined with apparent activity on 4chan, I'd say it doesn't seem just coincidental.
We don't know whether this has anything to do with the suspension though, everything that's being written is all just theories.
However, he is based in Russia and that changes everything.
https://old.reddit.com/r/StableDiffusion/comments/103vsm2/we...
As for 4chan activity, how on earth can anything there be attributed to anyone ? It's a anonymous messaging board. I can go there and claim that I'm the prince of Wales and start making egregious statements.