Kelly was faced with a similar predicament earlier in the game. LSU scored a TD and went up 13-9 xp pending. He kicked, went up 14-9.
Saban then scored and went up 15-14. Went for 2 (understand that here, probably EVERYONE goes for 2 here instead of taking the xp) and missed.
After LSU retakes the lead with a FG 17-15, Bama scores another TD. Up 21-17, not sure why you don't KICK THE XP here. 22-17 is just as good as 23-17.
My opinion, Saban coached like he was the underdog. If I don't make the first 2 pt try, I definitely don't attempt the second one when the gain was zero (FG doesn't hurt you, TD takes the lead regardless, but with you kicking XP you can at least kick a FG for the win instead of OT).
As for Kelly, I agreed with his 2 pt attempt in overtime. Win or lose on that play because I wouldn't want to get in a short field shootout with Bryce Young.