Because nobody even came to me and told me what happened, that's why.
When all I know is that a member, who is not longer a member of this community, alleges via third-parties that another member wronged him - what you're asking me is to play detective. And police outside activities between two parties, one of which is no longer a member of this community.
And to be quite honest, if you're going to do transactions with members, you should do so in the open. Like in a public buy/sell thread and keep the financial details to yourself. Then it doesn't become quite the "He Said, She Said" argument. And furthermore, don't deal with people in general!