Texas vs Cal near last play

[Texas Aggie]

I can think of no combination of rules which would give Cal the ball on the 1.

4-1-2-b-2: fumble that was loose. Replay could only determine that a TD had not occurred -- it could not determine anything further as there was no "clear
recovery in the immediate continuing action" per Rule 12 and the casebook. The Texas player picked the ball up and handed it to an official.

What combination of rules would NOT give Cal the ball on the 1 (assuming they don't score)?

By the way, unless there's a video or a photo at or near the goal line, we can't be sure. But I'm not convinced Cal didn't cross the plane of the goal line. The Cal player dropped the ball right when his left foot hits in the end zone. I'm not even sure how replay found indisputable evidence that the ball didn't cross the goal line.

EVERY other time we've seen this, it's ruled a touchback.

Maybe, but those were cases where the defense jumped on it immediately. 2 Texas players ran right by the ball and the third or fourth guy to make it to the end zone was the one that picked up the ball. He didn't run with it so he obviously didn't think it was live.