The thought (SF deferring because they forgot about the new rule) did briefly cross my mind. I’m not surprised some of the players didn’t know - for many of them, it’s not their job. But also, it’s like, don’t admit that, that’s a bad look. If the coaching staff and analytics team didn’t know - that’s a travesty. Shanahan immediately after the game said he was trying to play for sudden death on the third possession in the event of TD-TD, which would imply he knew about the new rule, but obviously if he didn’t at the time of the coin flop he would probably save face in the postgame.
And for those arguing about taking the ball first because the defense was still gassed… if your defense is still spent after a 5+ minute real-time break while switching to OT, to the point of forcing your hand on that decision, maybe you deserve to lose.
Chiefs FG at the end of regulation, kickoff, kneel downs, commercial break, OT explanation, coin flip, kickoff etc should be enough to let the defense recover.