Yes, make an alt on the server he transferred too and rub his/her name in the dirt.
There is no way to get a name change apart from people reporting your name for being inappropriate, so they will have the same name, easy to track down.
Now i’m not saying to bully and harass them as that is against TOS, now being honest about how much of a scumbag they are by telling everyone on his/her new server what crappy deeds they’ve committed.
Well they’ll get a bad rep really fast as there are only a hand full of companies that run any particular server.
Not having anyone to play with will kill their fun pretty fast.