This reminds me of all the criticism Madonna received (and still receives) for using guns on her MDNA Tour. People seem to forget guns are used all the time in movies, television, etc.
Moreover, if they're going to criticise Justin Bieber for posing with fake guns then where are their criticism on owners and employees of major toy stores that sell toy guns? Where are their criticism for parents/guardians that buy toy guns for their children to play with?
I dislike people that pick and choose what they criticise about.