g1smd - 2:09 pm on Dec 13, 2012 (gmt 0)
Now he's won on a minor point, you're beholden to delete every piece of content flagged in the future. If he's got the time, your whole site will eventually be gone. I would have told Google it was fair use and ignored the nutjob.
As far as I know, they have to comply with the request immediately, then give you time to fix it or deny it.
Oh, and don't delete a thread, make a hidden or non-public category in the forum and move threads or posts there. You can then move it back at some later time if you want.
With clever programming you can also make a thread invisible to certain users and the public, so that only certain logged-in users can see it.