Throw in case

[sj]

9.2.2.C - A1 scores a basket. After the ball goes through the net B1 grabs it and makes a move toward the end line as though as preparing to make a throw-in. However, B1 never legally steps out of bounds with both feet remaining in-bounds. B1 immediately passes up the court to a fast-breaking teammate who scores a basket.

Ruling: Cancel team B’s goal. Throw-in violation on B1. The ball was at B1’s disposal after the made basket to make a throw-in. B1 must be out of bounds to make a legal throw-in. 7-4-3; 7-5-7

I was trying to understand the specific violation here so would this be correct?

The ball is at B1’s disposal when it’s in his possession and therefore the throw-in procedure has legally begun. Then B1 threw the ball and the ball touched another player who was in-bounds which legally ended the throw-in. So we had a throw-in which started and ended but B1 was never OB. Therefore it’s a violation.