Possession / Touchback

[Sonuvahusker]

Could someone clarify something for me. It pertains to a play at the end of the Nebraska - Colorado game. A Nebraska player intercepted a pass in the end zone, and dropped to a knee. Even though his knee was clearly in the end zone, the official spotted the ball at the 1 yard line, claiming that the way the player was holding the ball, it was over the plane of the goal line. I believe the call was incorrect, using the following logic:

On a kick off, if a player receives the ball in the end zone, and drops to a knee in the end zone, it's a touchback. It doesn't matter where the ball is in this scenario.

Reason: The player took possession in the end zone, and never possessed the ball outside of the end zone. Therefore, dropping to a knee in the end zone is a touchback.

If this is true, the same principal should apply to the Nebraska example I gave above. The player who made the interception took possession of the ball in the end zone, never left the end zone, and dropped to a knee in the end zone. The correct call should have been a touchback.

Correct? Thanks for your help!