This remains a continual puzzle to me. (Behavior on DU.)

[TNLib]

7. My understanding is the officer has been placed on leave and it's under review.

The Atlantic

The Chicago Department of Aviation said Monday the officer who dragged the man has been placed on leave pending a review of the situation, noting his actions were not in accordance with the department’s standards. Though United Airlines CEO Oscar Munoz called the incident “upsetting” in a statement Monday, Munoz said in an internal memo to United employees that the airline “followed established procedures,” adding the passenger was “disruptive and belligerent.” He said the airline’s “agents were left with no choice but to call Chicago Aviation Security Officers to assist in removing the customer from the flight.”

I guess we'll know more once the review is conducted but it doesn't sound like the security officer was following standard procedures.

Though United feels it's employees where in accordance with their procedures.