I can appreciate the desire of modern communists to avoid a repeat of how things went with the USSR, China, etc. However, I don't think you can wholly repudiate the tankies as non-communist.
cacheson
Surprisingly, complaining in a community about how tired you are of hearing about the subject of that community doesn't tend to play well.
They haven't whitelisted kbin, so you won't see their posts (edit: unless they're made to non-hexbear communities). Only their comments on other instances, and a fair number have blocked them at this point.
I'm starting to doubt your ability to identify anarchists.
Y'all are very serious for a meme community
I don't think I can from kbin. 
, right?
They’re anarchist trolls
Maybe a few, but there's no reason to think that there's any more than that, let alone a majority. There's no shortage of actual tankies in the world, so why should hexbear be some elaborate ruse?
If I understand correctly, their posts and comments to communities on other instances will still remain visible to you until your instance specifically blocks them. Hexbear won't talk directly talk to kbin, but will talk to lemm.ee, and lemm.ee will tell kbin about posts and comments that hexbear users have made on lemm.ee's communities.