It's difficult to determine canon in the Superman franchise. However, in at least a few of the comics Lex Luthor has speculated that Superman is able to fly because (biologically) he can create gravitic fields around himself. This is apparently the result of evolving on a heavy-gravity world.
Not only would this explain how he is able to fly, but potentially also why he's able to pick up a bus from one of the corners without the full weight of the bus twisting and ruining it at the point he makes contact. His hand isn't really holding it up, but the gravitic field he extends outward is holding it at all points simultaneously.
This might make it possible to decelerate someone in a gentle fashion even when there isn't enough room to do so in a more normal fashion.
It explains many other things as well. Not only could it make him bullet-proof, but it might be able to make the clothes that he wears bullet-proof.
If this is an acceptable canon explanation, many bizarre and counter-intuitive events in the Superman franchise become more reasonable.