In asking myself what if I was in Jim's place, what would I have done. Well we don't know how the origination of the confrontation started. But I could say I never would have gotten into the starting confrontation.
With all respect for the upsetting situation that you've been placed in, without knowing how the thing started, I don't think you can know that you wouldn't have gotten into the confrontation. By virtue of your training and perhaps other life experiences, you have more options than Jim, and also more exposure to ideas that could allow you to see what options are available in a situation. Whether any of those options would have been available in this
situation is unclear, however.
It is always good for all of us to be reminded of just how easy it is to harm another human being, and how lasting the consequences of that harm can be. Whether experienced at first hand or read about on an internet forum, these reminders are deeply disturbing to any reflective and imaginative person, and so they should be. Our training can save us from some things. Our life experiences, in combination with our imagination that allows us to foresee possible consequences and outcomes, can save us from many more. Ultimately, though, we need to be humble and recognize that no matter how we prepare and no matter what we think we're capable of, life can always throw us a situation that we don't handle gracefully. We need to be humble, because in the end, life will always humble us.