She said police tried to escort Tabatabainejad, 23, out of the library after he refused to provide identification. Tabatabainejad instead encouraged others at the library to join his resistance, and when a crowd began to gather, police used the stun gun on him, Greenstein said.
Could you direct me to the part where it says he was leaving like he was told to do???
Sure, here it is
"At around 11:30 p.m., CSOs asked a male student using a computer in the back of the room to leave when he was unable to produce a BruinCard during a random check. The student did not exit the building immediately.
The CSOs left, returning minutes later, and police officers arrived to escort the student out. By this time the student had begun to walk toward the door with his backpack when an officer approached him and grabbed his arm, at which point the student told the officer to let him go."
Had the cops who arrived "a few minutes later" just let him leave as he was told to do and was doing, there wouldn't be a story here.