Not sure what "popping a guy" is? He stuck his middle finger up at Siver, but that's beacasue Siver refused to touch gloves after McGregor offered.Not touching gloves isn't really seen as a duche move. Pretending to touch and then popping the guy is frowned apon.
The point was that McGregor doesn't show respect, but he does. Ok he stuck his middle finger up after Siver refued to show respect back, but that's a different tmatter. You can't call a guy for not showing respect, when he clearly tries to.