Potentially every Steemian that sent money to @ bellyrub or @ bellyrub bank in the last 3month or ever could be viewed as potential witnesses or even co-conspirators.

Witnesses, maybe... co-conspirators, I really don't think so, since @zeartul is the only one that got away with stolen money.

And it could mean big hassles for Steemit if the Feds get involved.

Again, maybe, but I really don't think so. No more than say, Facebook would be involved if a user was soliciting deposits for a ponzi scheme on their platform. It's actually less, in fact, since there are no private messages on the Steemit platform - but other people have pasted screenshots with their interactions with them on other platforms (e.g., discord.)

Agreed, my suggestions in the post above are a long shot. But it's worth it to help make sure @zeartul is looking over his shoulder for a long, long time.

And like you said, someone might know him in "real life"...and cause him some real problems.