My thoughts exactly, the reckless people thing; it tends to be a habit.
When it comes to firearms, well I don't need to tell you I guess, an extra level of attention is required. I like your pellet gun thing although all mine are centre fire rifles. I expect this guy to be safe and responsible or I'd not be entertaining the thought of taking him but it needs to be verified as you know. I think my only he shoots plan should work. I can see how he handles the firearm, where he points the muzzle, trigger discipline etc.
I never use the safety prefering to close the bolt, pull the trigger, and then load the magazine which leaves no chance of an accidental discharge. When a target presents itself it's easy enough to rack the bolt and shoot quickly. I will ask him to do the same.
We'll see how it goes. I think he'll be fine and it might be good to have company from time to time.