the idea is not bad , but there's a thing that makes it useless
closed topics will not go up again as members can't post in them anymore
so eventually they will "go down" on their own
on very active/populated forums such as most of the trading grounds, this happens in a matter of seconds (max 1 minute)
but it wouldn't bother me one bit to have it the way you suggested it..would mean more work for minimum benefit

null vote