Dunno about strength per say, but it could be that he didn't think of it as anything out of the ordinary. Just not wired that way.
Sounds familiar, and I know this is your wheelhouse.
2 or 3 times, our closest neighbours foster child (maybe 11yo, with severe autism) wandered off in the middle of winter in just trackie pants, t-shirt and bare feet. It’s hundreds of acres of thick trees, deep gullies and tall bracken here. Huge searches were mounted, hundreds of volunteers as well as SES, fire and police all night with spotlights. Foster dad was clear that he wouldn’t be hiding, but wouldn’t come out if someone was close, and would likely be wandering down hill to the lowest ground he could find, and just sitting in a quiet spot.
Always took at least 12h to find him, he must have been freezing, but I can almost guarantee he’d sit there until he died of hunger or exposure. When found, he always happily took the persons hand and walked back with them showing no sign of discomfort or emotion.
Granted, it was always only something like 12-15h, but yes, wired differently as you say.