I like this. I haven't been back on GH that long after being away for a long time, but I have already felt the need to add one user (who shall remain nameless) to my ignore list. With this feature I could take them off ignore, and just flag their off-topic/thread crap posts as spamtastic instead, which would result in a benefit to the whole community, not just me.
IMO, I think this would result in cleaner threads that don't get derailed, not "group-think." It's worth a try if possible, anyway.