Action creates an equal and opposite reaction. The impact of the collision is the reaction to his momentum. He had protection so he was safe from the impact. The angels on the other hand didn't fare so well.
As unbelievable and unexpected as it is, he had no choice. What else could he do? He wanted to pass but they made it so that he would have to go through them. He can't pass through them or phase through matter. He doesn't have that power yet. So he crushed them and trampled over their destroyed bodies. Nothing could stop him this time, their blockade did nothing to hold him back.
The thing about motion and friction is that once the initial friction against motion is overcome, it becomes easier to continue moving. Soverick had broken that threshold of force needed to overcome the barrier that they created with their bodies, so it became much easier to trample through them.
