The fact that he was conscious at the star should have actually killed him (or at least he would have worse chances that leia). Normal instinct when losing air is to try and hold your breath, but then the rapid decompression would have ripped his lungs apart.

However, at the same time he is in a cloud of the air that was blown out, and he does immediately pull himself in.

As for the freezing aspect, the vaccum of space is actually apretty good insulator, so freezing isn't actuall a worry. And last of all, kanan wasn't as skilled in the force as leia, who possibly went into some sort of meditative trance rather than actually being knocked out.

There's a lot of explanations for different things about the two scenes.