Taking the safety was a risky call. Not saying it's wrong, but if the 49ers force Koch out with 8-9 seconds left, then they can fair catch and have a shot at a 20-30 yard OB pass to get them in long FG range. If you punt out of the endzone (even though a block is possible), you force them to score a TD.
Either way, I still have no clue what was up with that final return. No trickery, no formations, nothing - the idiot with the ball didn't even attempt to lateral it until he'd bounced off 3 tacklers and was on the ground.