The guy wasn't combative, non-compliant, or abusive until the officers grabbed him. He was, by all eyewitness accounts, leaving peaceably, albeit slower than the officers and CSO would have liked.
Have you ever heard of the "use of force continuum?" The idea is that you have a range of options available to you. From least severe to most severe, the continuum is as follows:
1. Officer presence
2. Verbal commands
3. Empty hand techniques
4. Intermediate force weapons
5. Deadly force.
The officer should use force in direct response to the threat presented, with the least amount of force that will accomplish the task at hand (in this case, having the student leave the building.)
The correct response would have been for the officers to enter the building and take up a visible position, such as by the counter (officer presence). If the guy continues to walk out the door, great! Everybody gets to go home. There was no reason to go up to Level 3 (grabbing him) and CERTAINLY no reason to go to Level 4 (tasering him) -- had they handled the situation correctly to begin with.
You didn't answer my question. You avoided it.