I don’t think he joined Sajid’s gang. He was there for one day to support Sumbul he would not have said anything to jeopardize her support. That being said he said some good things about Archana as well. We cannot judge him based on one day’s behavior.
As soon as he finished his conversation with archana he went inside to the bully gang and made fun of her asking him immediately about herself from outside.
So ...i don't think that very nice. What was the need for him to do chugli of archana. She was just genuinely curious...😡