I to think he was initially just being escorted out of the building.... not actually arrested. Until he started to fight back into the room repeatedly. At which point I think they were going to arrest him.

I don't know why they were even removing him from the room but if he had just left he wouldn't have been arrested but instead he fought and fought and fought and they finally put him under arrest.

I don't agree with the way the whole thing went down but he sorta signed his own death warrant when he wouldn't give in and just leave.