So you tell me who decided that technique.
Keith, thanks for sharing - it's neat to hear stories like this. I knew a lady who worked with troubled teens in a residential facility and she was learning aikido for use similar to what you did.
To elaborate a little on my belief of uke picking the technique, in a real over-simplified way I mean if you sense energy flowing to the right we don't do something taking them to the left, but follow the flow - I guess that's what I was saying. For instance, to me a kokyu-ho, kokyu-dosa exercise teaches sensitivity to nage as to where energy's going, to where an attacked is "vulnerable" in the sense of where we can help them go - up,down, sideway, backwards, forward, etc.
I'd say the guy charging you picked it. Given the space constraints, it was probably the only option, though, open to you, absent taking him forward into a person or wall. Yours definitely did two things: ended agression, and did it with compassion!