You apparently don’t read.
The very beginning of the law says:
“An individual on an aircraft in the special aircraft jurisdiction of the United States who, by assaulting or intimidating a flight crew member or flight attendant of the aircraft,”
It means ONLY if a passenger “assaults” or “intimidates” a flight crew member. He was the one who assaulted or intimidated anyone, it was the other way around.
In fact, United own terms of service do not allow for involuntary removal of a boarded passenger, except if a behavior of a passenger causes that removal for reasons of security or safety. Wanting his seat to give it to someone else is not provided as a condition that can warrant involuntary removal of a boarded passenger.
The WRONGFUL “assault” and “intimidation” came from the United employees, who at the time were unfortunately following a rule book that actually contravened their own terms of service that apply to the ticket. Munoz rule changes are actually correcting them to conform to United’s own written terms of service.
That's the statute you'll be charged with, acquitted or not.