Unless you can prove that they are RMT, like they share accounts with known RMT, you can't say shit about whose mule it is. You're applying retarded logic, that just because you wouldn't sell an ulli stone that no one else would possibly want to sell one.
It's just like the claim that you got temp banned for hacking. There was no proof that you flee hacked, in that no one reported seeing you(as far as I remember at least). There's some enough circumstantial evidence to point to they likely did buy from an RMT mule without knowing the owner for some of their stones; due to the lower amount of people who would sell the stone. The same kind of evidence that "proved" you were banned, namely your refusal to log on for the few days of the ban. In neither case is anything actually proven, just blatant assumptions made and followed like it's gospel.