At the moment it is his job to start the roll not benefit from it. He was purchased for that reason. The good props start the roll with their size and speed hitting the line and bending it. Snowy is that slow the defensive line gets to him just after he touches the ball.
I agree he needs a bloke to get the roll on so he can benefit - there is absolutely no doubt there.
This has a lot more to do with the play the ball and dummy half. Technically if he was quicker the defensive line would get to him quicker again. The line are up in his face because they know he is getting the ball with no other options as decoys or possible receivers, and they know he will take the tackle with nobody to pass or offload to so they can commit as many defenders as they like.
So is it Scott that benefits from Tamou? or Tamou that benefits from Scott? cos they can't both start the props rolling with the first hit up?
Also, as an aside, the fact that both our wingers come in early in the set to take the second and third hit up means that we can't spread the ball to either side until the fourth (this is more evident because we play most of the game in our half. This means teams can bunch in the centre do defend in numbers against us without risk. A couple of times Willie made good ground going round the outside but there was no winger to pass to in space cos they took the last hit up.