I also traded MY MW Heavy Lance and +1 mail gauntlets for a MW Lance. I knew I could have sold my +1 gloves for like 200-300k, and probably only given up 100k or so for my MW lance, but I wanted to get rid of that shit weapon ASAP. I didn't consider myself getting screwed (4 looms in items for 3 looms in an item).
Some people are the opposite (like Witchcraft), if he wants to put offers like that up, it's up to him. If someone wants it they will buy it, if not, they won't. Why would you suggest he be banned for legit trade requests?
Sorry you don't like his trades, here's a great solution for you: Don't accept them.