I think that David actually got powers. When I read through the portion that Prof gave David his powers again I noticed that David spent the next while wondering why they didn't work as expected. For example - he blamed his survival on Profs powers, but got confused when it didn't hurt to breathe even though the profs force field would do nothing about the heat. He also healed a LOT more then it seems like it would be possible with the profs powers. The entire time it looks like he is developing his own powers, but has no idea.