nah, i don't think they are deliberately keeping the name from us. i stick by what i said about legal issues contributing to the delay. If they do decide to announce the drummer till after the album is out, it would probably only be because they got the greenlight to do it right before release, then simply decided to wait.
the only other reason, which is probably less likely, is that they might be withholding the name till right before the albums release, then announcing it, subsequently creating a huge publicity buzz and thus boosting the sale of the new album due to intense curiousity. like i said though, unlikely.