For my
he is no more or less annoying than you and your self bumps and "$4k offers" received by email on your "ultra premium" domains.
It is actually pretty laughable that you would make a thread crying about somebody doing the same thing you do.
He is in the buy/sell section, so he is in the right place and anybody who wants to buy something looks at several pages not just first 10 items.
I hate to break it to you but that guy bumping the thread is not the reason your domain hasn't sold
