'Problem:
disruptive person onboard.
Not proven.
Solution:
diversion, offloading of said disruptive person.
A purser was definitely disembarked (the basis of the questions and arguments in this thread).
Costs:
one hour delay on arrival plus handling cost at diversion airport.
You seem to forget that passengers actually pay wages. The inconveniencing of a large number of people plus the reputational cost to UA.
This diversion may also cost a Captain his job and may potentially blight the careers of the First Officers and the Cabin Crew.
Benefits:
safe and smooth remaining flight.
Not proven. Questions about the crew's (not only the Captain's) competence to complete this flight remain.
I would say much ado about nothing. '
Stick to Shakespeare, your logic is flawed.