The ODP probably doesn't have the people to deal with this. I recently became an ODP editor of a piddly bottom level cat with 9 sites listed because I was so disgusted that 3 of them LONG had been dead, and were just redirects to other sites. Robozilla never picked up on this even. Google did however, and in the Google directory those 3 sites have no PR. Obviously once a site gets in the DMOZ, even if it goes bye bye it can stay around indefinitely.