People need to understand that using something obtained legally before the street date does not violate any rule or law, and is not cause for a banning unless the company wants to expose themselves to a lawsuit. The occasional reported banning is expected, when it is mistaken for piracy or someone simply makes an error. But really most of those people are simply lying (I think Halo 4 guy was banned for using a physical, but stolen, copy of the game.) Can Microsoft ban the X bone guy if they want? Yes, in the sense that no one could stop them. But legally, they simply don't have the right to.
Punishment for playing early is an urban myth, period.