>>718837048
That is the first step of what he is saying. If the folded space does not give momentum and cause things to move, then the thing will not move. The next step is that if the thing does not move, the folded space will reduce the distance between two points of the material, which creates a force that will push the material out of the portal. It would be the material itself that causes the momentum. For some reason when people say that the cube doesn't move in A, they just accept that the cube actually will move and then stop rather than that it actually simply won't move.