This has me wondering as well. It isn't like any company (whose primary focus is to generate revenue) to simply cut out a portion of their profits due to a moral compass suddenly run-amok as the result of a recent tragedy.
Either these companies are receiving encouragement (pressure) from somewhere, or they are fearful of future boycotts. I'm guessing the former because I find it highly improbable that they would preemptively counter boycotts that haven't happened yet.
It will be interesting to see Wal-Marts moves in the coming days.