Think about it: When you spend 20 years of your life doing something, it tends to get rather thick. It's who he is, what he is, and he likely will always identify with them. I had a friend in the 70's (you could probably have described both of us a graduate student hippies by then) who had been through the first session of Ranger training but opted not to continue when it was over & returned to his normal infantry unit. It was an accomplishment just to complete those first few weeks of training. It's not at the top of the elite food chain, but it's up there.