As for who, who knows. I'm not going to reveal specifics about pms I've seen in reports here, but I will say it's not wise to taunt scammers when you leave them negative feedback. It's disrespectful, and a good way to make enemies.
I am sure that a lot (or at least some) of the people that receive negative trust is a result of a misunderstanding and may not truly be trying to scam. If this is the case then taunting after giving negative trust means that you are taunting someone who is trying to operate legitimately.
Imo that behavior is very unprofessional and reflects very poorly on him.