The trigger guard is exposed . I think it scared him a bit and he wanted a holster that covered the guard.
"Back when..." as you probably know, just about everyone (including the FBI) carried double action revolvers in holsters that exposed the full trigger guard. This was safe enough considerig that most revolvers had double action trigger pulls that weighed around 10 to 12 pounds - and sometimes more. Also if the rig has a safety strap (conventional or thumb-break) you can't pull the trigger on the holstered revolver because the hammer won't rotate backwards.
Jeff Cooper started this "cover the trigger guard" business when cocked & locked 1911 pistols became popular, and when the Glock arrived the need became obvious. However neither of these pistols has any connection to double action revolvers.
When I was very much younger, and therefore knew everything there was to know, I had a conversation with Col. Charles Askins, who had been in far more gunfights and shootings then anyone else I had met, or would ever meet.
I pointed out to him that, carrying a revolver with the front of the trigger guard cut away (as he had done) "was dangerous." He looked me up and down and I got the impression that I might have made a grave mistake. Then he replied, using language that Art's Grandma might not approve of, "That if I ever got into a shooting and survived, I would discover that there a a lot of things that are more dangerous then a cut-away trigger guard."
This matter of exposed trigger guards on holsters designed for double action revolvers would have undoubtedly gotten the same answer from Askins as the one concerning his "Fitzgerald-style trigger guard." Your young friend has a lot to learn.