The fact is that trust isnt moderated and you will have to leave it as it is or deal with him to remove it. Plus that you cant call him abusing it because he is not in the Default trust list and his trust feedback pretty much wont make any impact to your account. Suggestion for you would be to leave it as it is though ( I even got mine as well from some butthurt user )
P.S : Besides that he seems to misspell the site's domain
Doesn't matter if a user is in default trust list or not. He has no right no leave negative feedback for no reason. I still consider that as a trust abuse. Let's say that someone wants to initiate a trade with me. He might check my trust feedback and when sees a negative feedback, he might hesitate a bit.
But it doesn't matter. I don't mind that negative trust and I don't wish to contact him as he sounds like an immature grownup 20 years old guy.