Time is either up or it's not. The ref has no descretion, this is specifically stated in the laws of the game. I know what I'd think if we conceded at the death this aft and it was after time had expired, but the ref was waiting until the ball went out.
How did he know it had expired just as the ball was flying into the net without bothering to look at his watch?
I don't know, I wasn't there. I didn't make the rules, I'm just confirming what the rules are. Many people think that the ref can extend the game until the next stoppage, or until play is "neutral". That's simply not true. And by the way, the ball spinning over the line from the penalty in added time will count - the ball is allowed to touch either post and/or crossbar and/or goalkeeper before entering the net.