If it's one dude multi-boxing: if he wants to pay for half a dozen copies of the game, then half a dozen sub fees when it goes p2p then more power to him. He's going to be insignificant anyway.

If it's RMT: You simply have no hard proof. SE can't ban on vaguely interpretable screen shot. How would you feel if SE perm banned your account because some random person took a shady screenshot that was misinterpreted?

The way they've screwed DoL levelling is a bad enough measure against RMT. I won't even play the classes.