Any thoughts?

I don't think so, you get physical things with real effects.

I guess if you want to percieve it that way, go right ahead.

But you can't get holy hand grenades from hallucinations. :shrug:

If it was all in his brain he couldn't die by the old grannies with rolling pins.

It could, (at times maybe should); but in general... Why? Its supposed to reflect.... well at least in the original games it seemed a satirical poke at how truly unknown the wastelands had become; a kind of "thar be dragons" / "spit-take event" to break up the unrelenting oppressive malaise of the setting. The same goes for certain NPC and dialogs ~whether they were silly, serious, or just oddly memorable.

Many special encounters in FO1/2 could be looked as partial hallucination, or not; or an just encounter with other hokerrs lost out there. The biggest difference is that in FO1/2, you could never find your way back to them, and could never be sure they had happened at all... It could have been a mirage from heat exhaustion and dehydration... You didn't really see a swimming pool size footprint in the sand [Did you!?] with a flattened dude in the center of it (wearing a ring) ~but where did this stealthboy come from.

Players should not read to much into it, or try to overly explain it; but... it could have just been an odd depression in the soil / natural, and a traveler (perhaps a merchant) fell dead there, and the PC stumbled delirious onto the scene... Fallout 1/2 implied DAYS or WEEKS of harsh travel through rough (and sometimes irradiated) country to get from one town to the next. This whole aspect is lost in the later games, and IMO requires a different method or style for the bizarre encounters. For one thing IMO they should fade with a cell reload, (or within a few game hours); One should never be able to walk back past the fridge and think, that's where I found Indiana. That's another problem though... The series never let you know with pinpoint accuracy where you were; so when returning to an encounter (like with Indy's fridge), it could have been over the next hill and you don't know it, and you just don't see it anywhere anymore. The new games give GPS satellite like maps. IMO this ruins the humor a bit and implies that everything is as you saw it, and you can return to it for a closer look just to be sure.

One can die of fear, and / or shock... One can also run off a cliff trying to escape an imaginary attacker. :shrug:

Maybe they were perfectly normal encounters that got messed up while getting to his brain...

Like three raiders or assassins showed up with knives but he saw them as old ladies with rolling pins...