To be fair...the opening line of the op is should this happen. If you didn't want people giving their opinion of why not, you shouldn't have asked the question.
Don't ask a question if you don't want an answer that you don't want to hear.
There is plenty of light hearted banter and roasting goes on in the chat threads so if it is to be as light hearted as you say, why do we need it?
Personally I think its not a bad idea as only people who enter the thread can be targeted but I don't really see the difference between this and the chat threads anyway?