You're right to distinguish between Julie and Matt's roll in the hay and Riggins' drinking. But let's forget about his bad habit for a moment and concentrate on what he was trying to accomplish that night with J.D. The way J.D. and his dad are operating, J.D. is a menace to the team. His dad is in it only for his son and does not want him to be contaminated by the rest of them. This is ugly, mercenary behavior and the worst of football. It's the opposite of what Coach Taylor wants for the team. So Riggins was subverting Mr. McCoy's influence in the only way he knows how. And there's precedent in Riggins' humanitarian party missions—remember the time he saved Julie from that skeazy guy at a party? Once again, Riggins is sacrificing himself for someone else's sake and getting no credit.
As for Smash and Riggins—you are absolutely right. This is more proof of the point Meghan has made. Riggins used to have a dangerous, almost racist edge. Now he's gone soft, as have all the boys on the show. Matty kicking those boxes is the most male aggression we've gotten this season.