It was Waud who fell on Gable. While the hit was unnecessary because Gable was already headed for the turf, I don't think it was illegal or even unusual.
But it does typify a subtle change in the game over the past couple of decades, in my opinion. Players used to hit to make a tackle. Today they hit someone if they think they can get away with it, whether it contributes to the play or not. It is very common to see a second or third defender throw his body at a ball carrier that is clearly not going anywhere - as though the centimeter of progress they may have prevented is meaningful. Several years back as this became prevalent I would always be waiting for "piling on" flags, but they never seemed to come.
In Waud's case, he wasn't even trying to prevent further progress - he was just trying to throw his weight on top of an opponent who was already stopped. Because he could. Because everyone else does it. Because they all need to prove that they're tough guys. Because the refs don't care - they are too busy looking for incidental contact on pass routes.
I think that mentality is one of the reasons we have so many more injuries today in the CFL than we used to.