Went as a volunteer to a camp for kids with ADHD and Aspagers. Tantrums are unavoidable. We had drafted a contract with the kids that lines out rules of conduct for pretty much everything, ie. swearing == 10 push-ups or squats, any attention seeking behavior had to be diffused with holding and counting down from ten. It was ranging from a symbolic hand holding up to a full ground tackle if the situation was going a bit overboard.

IMHO you acted the best way you could. I've seen to many kids traumatized by a lack of a framework that would allow them to think about consequences. The key is communication and respect for the rules from both sides.