One of the things that we tend to forget about movies is production values, limits, and costs. Rocco became at some point in the movie a prominent and recognizable character who was meant to be so recognized by viewers as such. In that capacity he was sent to murder Roth. I don't think it had anything to do with any imagined treachery by him. There's no basis for that at all in the movie.
And PB's right. You just murder a traitor. Why take the chance that he's going to turn on you with a gun or testimony or alternative allegiance?
Last edited by olivant; 02/14/11 11:50 AM.