This was far too much and he crossed the line. He is only responsible for his own action no one else. And I wonder about the gall that he exhibits here.
It is true that people on the show all treat UpMa badly. People feel freer to have outbursts against them, question them,, etc. Even the host was quite rude to them. This sets up a climate that a wimp like Chetan can do such a disgusting gesture. He is taking advantage of a climate that exists. Would he dare do this with Pretty? I doubt it. He is piggybacking on others being mean to UpMa.
Chetan is disgusting and only he is responsible.