Okay, he’s harmlessly strangling him. No ones ever been hurt with harmless strangulation.
This technique is practiced thousands of times all across the country in jiu-jitsu and judo classes without incident, and even more so in no-holds barred fighting sports. No restraint technique is perfectly safe, but cutting off air by closing the trachea (e.g. choking) is MUCH more dangerous because of the risk of collapsing/permenantly damaging the trachea. Also, the carotid choke takes less than ten seconds to put someone down, so the risk of over holding the choke resulting in dangerous complications is reduced as well.