Squall is lying motionless because he just passed out from exhaustion. Though I'm curious how you determined he wasn't breathing, given the short time he is focused on after his fall.
Rinoa holds him for a while and we can see clearly that he is not breathing and he is focuses very steadily.

Further more he didn't "pass out fro exhaustion" he was effected by Time Compression.

Anyone else want to motion this to be a thread of it's own so we can get back on topic?