Dawn beat me to it, but I too would tie motorcycling to firearms experiences. Some of you know that many of my weekends are spent at race tracks instructing at full speed. Errors happen. Mechanical failures happen. People get hurt. The hardest part for most people isn’t the healing, but the coming back to the sport after with that issue in the back of their heads. If one let’s it, it can get in the way of again working toward proficiency and safety. A close friend is working through that right now, after having his collarbone put back together…an injury he sustained which he could not have avoided (Seven bikes went down when the front bike blew and engine and oiled the track. There was nothing to be done by anyone). It can easily turn into a case of the “What Ifs.”
It sounds like your friend is well on the way and being extra cautious, which is good to hear. If uncomfortable about discussing it, he could always use the old “I have a friend who” or “what if this happened” with any person he wanted to address the subject with. Negligent discharges are rare, and injuries from them even more so. Always pointing in a safe direction seems to be a big one here and could have saved him a lot of trouble; something that we can all learn from.