[MicroBob]

They should also be able to provide him with all the HH's as well as the names of the players who they believe he was colluding with.

They should also be able to tell him exactly how much he won from each of those colluders.

Still a chance that he happened to sit-in with a team of colluders and just happened to beat them.
Seriously, I can see how this could happen.

3 or 4 guys team-up with some stolen credit-cards or whatever (or 1 guy with multiple accounts and/or computers). But they happen to be sucky poker-players who all lost some dough to a half-decent player who had no awareness that he was playing against a team.