White vinegar does work and I've used it, but not by pouring it on the snake's head! Just apply some to a cotton ball and put it in front of the snake's nose to get them to turn you loose.
I'm betting that if your king grabbed and held that the kid's hands smelled like food. It doesn't have to be rat or mouse smell, my Cali King went for me after I'd picked steamed crabs.
Also agree you need a lock on the herp room door, or on the enclosure door if it's in a public area.
If you can still smell the vinegar on the snake I'd give him a quick bath and keep an eye on him for a few days.