No, it's definitely not proof.  It's more like evidence that could be something or might not be--but props to OP for at least looking out for cheaters, because we all know they're in the walls of bitcointalk like termites.

The merit sending does look a little bit odd, and I wouldn't be shocked to find out that the members involved are alts or are part of a bounty farm, and I'll always have a fondness for this pic:



There's a lot of money to be made in bounties (and in having a ranked-up account), so no doubt there's merit abuse happening.  Whether it's happening with the members named in the OP I'm not sure, but it's definitely something to keep an eye on.