Only 2 of all the banned accounts have been flagged as sock-puppeteers. You can't see the sockpuppetery anymore because the mod deletes their posts/comments. But the evidence is still there as negative points. Those profiles have negative points. So they must have posted something sometime, got downvoted, got flagged by users and got detected as sockpuppets.

Sock puppet is only one possibility. Other possibility is legit accounts forming a voting ring. You and me cant see voting actions. Mods can.

The mods have access to server access logs. Mods can see who +1-ed whose posts/comments. So if you need evidence for sock-puppetry or voting-ringery, try asking the mods about it. We can only speculate here. I'm only describing what I've found in the wild from my days of moderating (small) forums.

I mean to say that only because you can't see the other accounts posting related posts/comments does not make them any more likely or any less likely to be sockpuppet or voting ring. They may be legit. But they could be a ring. Or they may be legit. Only the mods with the access logs can tell.