but at the same time it contradicts the established rules, what are your conclusions?
How's exactly account changed hands contradict the rules? where's the rules saying that account changed hands should be banned or red tagged?
18. Having multiple accounts and account sales are allowed, but account sales are discouraged.
Since the account doesn't have any reputation (green trust or DT1), not participate in signature campaign nor bounty, offering service, taking non collateral loan etc, I don't care with that. He's not making any mess or taking advantage over his account, so I'll just leave it.
This is about the answer I expected. It is impossible to prove that the account was sold, and if nothing besides the sale contradicts the rules, then there is nothing to add.