You aren’t a police officer and never have been, so any booting you did of my daughter without a lawful reason would be assault.
She was kicked because she was actively breaking the law, consistently and wasn’t stopping, she continued to pose a threat.
That officer had just witnessed her assault an officer and obstruct a police officer in the execution of their duty, I and I suspect a lot of other officers, past and present would appear eminently reasonable.
I think the written warning sends a message to officers that you won’t be supported when you assist your single crewed colleagues who are in trouble.