Offer him a 10% discount on a membership. :)

I would not even consider it being an ass if you did nothing. You are a professional and bought the name. Screw him, he can wait in line for it to expire like everyone else or make you an offer. The only people that I know of who can TM human names, are famous ones. Besides if you just decided to give him the name you are also giving him any work you put in the site, and all the traffic what is and will go to it over the years. Tell him to make you an offer, when he comes back with the $8 go daddy bullshit, just say thanks but no thanks.

Tell him to go pound sand.

I have seen my name in credits in hollywood movies, (Which is really common. There are 4 alone in the city I live). doesnt mean I am going to go after those other and ask for a payment.