Maybe add a resolution of NEEDMOREINFO?
There is no need to add one more reason for a bug resolution IMHO, INVALID with appropriate comment does the job.
INVALID seems harsh, it may scare away novice reporters.
Do we want to make it easy to search for bugs stuck in a needmoreinfo kind of state? If so, a keyword or state might be handy.
Does anybody remember good old gnu gnats, the old bug tracking system? It was great this way; it had an explicit notion of whose ball the court was in. I miss that. - Dan