The guy clearly got hit in the head while he was in Nipton because if you leave him alone, he leaves the road and just runs out into the wasteland, getting himself killed by radscorpions.

It's been a minute since I last played, so maybe there is something like that by now but I've felt for a long time that this game needs an NPC overhaul along the lines of Immersive NPCs for Skyrim. Just for better schedules and shit.

I'm thinking of that lady that you save from geckos right at the start, who just spends the rest of the game standing around in Trudy's house. Or Malcolm, who appears out of nowhere, then vanishes into thin air after getting to the Mojave Outpost. Same with those star bottle cap people near Nipton. Not sure how much this old engine allows though.