Unless you know the player personally I doubt you'd know if he got banned in any case.
I spoke to a GM and he said it was bannable if it was clear the person was purposely griefing, which I guess means trolling in chat or laughing at people. Whenever i've seen somebody purposely wipe (which tbh i've seen like 2 times since LFR was introduced, maybe i'm lucky), they had to tell everybody in chat how funny it was and what they were doing, the flaw of the bad guy always revealing his evil plan.