Look, it really isn't that difficult.
Kid distracts everyone
Kid doesn't shut up when told to
Teacher tells kid to leave the room
Teacher adds unecessary comment
The difficulty comes when you consider how irritating the kid must have been to make a presumably seasoned teacher to speak out of turn so early in the school year.
No, the comment was not justified and the techer will know this
Yes, the comment was probably apt, but still should not have been said
Yes, most of the kids in the room probably agreed with the teacher
Yes, said kid is probably embarassed and upset by the implications - maybe enough of an unpleasant wake up call, you never know
Solution? OP - speak to the HoY, tutor, whomever!
You need to find out why your child is pushing staff buttons so hard, so early and what the school is doing to help him stop pushing! And yes, that includes a stern word with the teacher, he needs to rethink his approach too!
An easy way to start is just to pick up the phone and ask for an appointment!