I think no. Even when posting we do allow empty titles (I think), we only don't show the submit button in the form unless you enter at least two words for the title. This feature is for monks who accidentally forget to fill the title, or for clueless newbies. No amount of administrative measures can force monks to give good titles, so if someone really wants to edit the title of his node to empty, we should let him.

Update: in addition, the ban on single word titles is also a measure against nodes with identical titles, as that could hinder linking and navigation. How do I compose an effective node title? states this explicitly.