I also think the kid did reasonably well. He didn't fold although he was clearly dominated, and he tried his stuff (sure Silva could have knocked him out at any moment, but that's not the question).
I also don't see anything disrespectful in a spinning back kick. It's a sparring session, it's there to try things out that usually rarely work in competition. He makes the best he could out of this opportunity, what's he supposed to do - throwing some jabs and then sit down again¿