It's clear to Don that he barely has enough strength to push Raph over, even when he's in a position that maximizes his leverage. If he tries to avoid Raph's tangling move, he'll lose his advantage entirely.

So he goes with it. But, on the way down, as soon as Raph is past the point of recovery, Don lets go of his leg and throws his arms forward, using them both to catch himself and to limit Raph's maneuvering space.

If he has any time after they hit the ground, he'll shift his weight to one arm and aim a strike at Raph's face - the kind of strike that would crush his skull if done with real intent.