Tom didn't punish Danny

So I get that Danny was Tom's childhood friend through it all, but he as insinuated as the person who filmed the rape. It makes sense, he's kind of higher up in the gang so he would be aware of the rape, probably even was there. So my question is, why the hell didn't Tom punish him. The only 'punishment' he seems to dish out to him is tipping him off that he is aware that he probably filmed the rape and to watch his back. But, that some how doesn't seem like enough of a punishment for what he took part in.