I'm sure there are always some people looking into 4chan as a place to spread an agenda due to the ease of posting, no need for an account, popularity, etc. However, banning for "anything remotely against russia and china" is a silly exaggeration. Giving you the benefit of the doubt, my best guess is that you posted on some of the boards with tighter moderation, and what you posted was simply off topic. Most boards still prune off-topic shitposting somewhat reliably.

Not to the exclusion of other peoples, you can find plenty of gleeful posts about the brutal deaths of Russians and Chinese, or just simply mocking their societies/industries, at any given time on at least three boards, off the top of my head.