Yep...You’re right.
It just looked like he had possession go the ball and I would have called him down at the 1-yard line, and thus ineligible to advance the ball any further.
The ruling on the field was correct according to the rules agreed to before the game started...
Ouderkirk, he would be down as you have described in college football. But in the pros, he’s not down until he’s both down on the ground and the defense has touched him. But other posters have made the observation that the receiver does not complete the catch until he has maintained possession of the ball “through” the entire fall. That didn’t happen as the ball both hit the ground and moved in his hands. That’s the current rule like it or not but the interpretation was correct. Close but correct.