Soft-ban? So we're just going to frown at people who pick him on the PS3 consoles?
It's either ban or no ban, in my opinion. I'm fine either way, but for people who only have an Xbox and play BB, it is somewhat unfair to them on one hand. On the other, it's the same as if you had never gotten specific match-up experience with a certain character in any game.
While there is no way that people could have fought Valk on Xbox, there's also the other side of the coin. It's really up to you guys but I don't think there's any real point in soft-banning, unless you mean hard-banning him for this event and this one only.