IF I were a coach or administrator I wouldn't want the players to do it. there are other ways to pay tribute to a teammate facing rape charges that keep it out of the public eye. I would keep it "in house".
This kind of brings another question. When did writing on yourself become popular among players? Does the NCAA regulate what you can/cannot write as a message on your body? I think its a bit different than tattoos. By no means do I think writing JJs number will draw any concern from the NCAA or DOJ. Just curious about the whole writing thing....looks a bit hacky to me regardless of what the message is.