I would agree with the reasons Bealzebub gave above.
The company didn’t previously ban the passenger from travel so they are happy for him to travel, provided he behaves. At the point you removed him from the flight he had not caused a problem ( or you have not indicated he had ) so you had no reason other than previous history , that the company had accepted and delt with, to remove him.
This one is down to you in my opinion. Hopefully they understand your reasons.