Spence wrotehad the opponent not clamped down on his arm and then caused him to go over the offensive player's back.
Just saw the replay again on ESPN, and it sure does look like Blair continued to pull Thabeet over his shoulder by leveraging-down on his (Thabeet's) wrist.
Blair initially had both hands on ball when Thabeet had stuck his hand in there.
But then as Blair leaned/crouched forward, his (Blair's) right hand comes off the ball and he arm-pulls Thabeet over his back.
The replay really makes Blair's tug look intentional.
Granted, lead-official was screened from this by Thabeet and center-official was already headed down court (eyes probably on mid-court group of transition players).
But, hey... I'm just some high school official who happened to be lying on the couch eating Doritos when he saw the replay...😃
Paul