I think since he draws an analogy to a problem it would be actually absurd to work on (no point working on overpopulation on Mars unless several other events happen first), he does seem to be suggesting that it's ridiculous worrying about things like UFAI now rather than "hundreds, maybe thousands of years from now".

Anyway, I only thought the post was interesting from a PR point of view. The AI problem has been getting good press lately with Musk/Gates et al suggesting that it is something worth worrying about. Ng hasn't said anything that will move the larger discussion in an interesting direction, but it does have the ability to move the whole problem back very slightly in the direction of 'weird problem only weird people will spend time worrying about' in the minds of the general public.