Based on the idea that I'm the average age of a cop and reasonably healthy,On the surface, maybe. It's very hard to judge from afar. If the 'stand back and do nothing" approach might lead to the kid killing himself with head banging, and the "make an intervention" approach resembles wrestling a rabid raccoon, where both you and the raccoon might become injured, which do you choose?
I think I would come from behind, hug the tiny person, back into a chair with him sitting on my lap, and wait for him to run out of steam.
But then, I'm not trained in the escalation of force and a 7 year old can't make me fear for my life.
Personally, I would never fit in that kind of job. My temperament is not suited to it. But I can think of methods more suitable for people under 80 pounds.