"If you believe that life is meaningless, then it was OK that that young man down at Virginia Tech did what he did."

Life is meaningless from the point of view of the universe in general...it is just a thing that happens when certain physical laws operate....but it is QUITE meaningful from the viewpoint of sentient beings - who GIVE it meaning in proportion to their degree of awareness.
   The victims at VT would have 'chosen' to avoid their sad fate...the shooter gave life meaning BECAUSE he felt that depriving others of their life meant something to him.

Moral laws are not hard to describe, defend and apply, even with no 'ultimate' meaning.