RMS is just too busy with more important things like software freedom in general and needs to delegate. BTW, it's not as if RMS has always been the _maintainer_ of Emacs--from the acknowlegements:
"Gerd Moellmann was the Emacs maintainer from the beginning of Emacs 21 development until the release of 21.1."
Yet RMS has had a decades-long involvement with Emacs. It seems he will continue to be involved, so what's the big deal? More generally, GNU has always been about freedom first, development second.