Google aren't silly. They do a lot of testing. I am sure they would have tested giving a DMOZ listing an extra weighting vs not giving it an extra weighting. They would have determined the effect of that on the global quality of the search results. If the results are generally better with the extra weight for a DMOZ listing, then they will use it --- that has nothing to do with how outdated DMOZ is or not or how many potentially good sites are not listed or not etc .... its all to do with the results of Google's testing and the impact that it might or might not have on the search results.