we don't really know that though, David could have been lying or simply NOT detected the other living Engineers....remember, he had to find that underground cockpit chamber, see the log of what happened, and THEN put his ear up to that stasis pod to really know for sure someone was still alive in there...he SAID dude was the last, but if there are all hese other ships, how does he "know" they're not still alive....IMHO i think David was really trying to further the Engineers agenda, and it didn't work like he thought....other than his seeming affection for the doc, he seemed to detest the other humans on the ship.....