I mean, where were you guys withholding mods before that did the exact same thing..? He did nothing wrong.
We often withhold submissions for the exact same reason I withheld that submission. However, there is a lot (and I mean a LOT) of content to sort through on this site, and it does have a tendency of slipping by now and then. If the submission is old enough, we'll usually fix the credits ourselves, but newer submissions should normally be fixed by the submission owner if the credits are not showing properly.