Wouldn't see a reason for a ban if it was done in a fashion accepted by both parties and in an rp manner.
Yep, Vaka simply abused a mechanical flaw, his so called RP was never accepted by the other party, hence, no acceptable play, thats not RP but meta-gaming.
If you want to play a baddie, do it well, play well and thoughtfully, fair and benevolent. If people see you are playing that way, having put some good thought into your plot not the last to entertain others, they will want to play with you. They will be less suspicious about you only trying to make money in a cheap, poor and OOCish way. Its that easy, entertain people and they will reward you.
As for that Xiosia "hoax", who is whining? If your char believes he wants to sacrifice everything he has, he has to do that (and go through DR which however seems to have become a joke - Settings anyone?), even if it would be your char to whine at last. But if you as a player has to complain in the end, then heck, you didnt get the idea of roleplaying.
Playing a character under the intention of trying to have him/her be evil means that you are meta-gaming. Don't meta-game.
Uhum. Taking you by your word, if I wanted to create and play an evil char, thats meta-gaming? I had rebellous chars, goodwilled chars, naive chars or also insane chars, all of them from scratch intented to be like that furtheron. I never mixed knowledge of one to the other, and each of them I gave my best to keep them consistent - now you say thats meta-gaming? Dont you think your quote is pretty much BS? Or do you think a player is only legitimately allowed to play a char right according the player's personality is?