I don't think that is legal. (Not saying it is illegal)

Negative - You were scammed or you strongly believe that this person is a scammer.

Technically, Vod has the right to put it as long as he believes that such a trade might result in a scam.
Otherwise, you will only consider it a scam only when the scam is done over with? It is a warning, lol. I don't think you will get it removed, IMO.



Edit: The trust feedback was probably given not because of MS Terms, it was given because there are quite good chances that all the keys may be revoked.