Thanks, lots to unpack there.
Retracing the route of the Chung-Gerrish family: I might do something like that, though I accept the coroner's determination. Not fully clear if he's a conspiracy theorist or not, or what he hoped to find.
Hiking alone: Not ideal, but never a deal breaker for me.
Getting lost: Doesn't everyone have GPS these days?
Hiking in late June despite the family having died of extreme heat exhaustion: Not very smart.
Not leaving word as to where he was going: Not ideal, but I've done that a time or two.
Chatting up a stranger at the trailhead: May have saved his life.
"wearing sweatpants 'on some of the hottest days we have seen this year'": Opps.
Hiking on a "CLOSED" trail: I may have done that a time or two.
Carrying two gallons of water: I may never have carried that much

, good for him, but I do carry a water filter.
Getting dehydrated despite drinking from a river: Dumb, if it's going to make you sick the amount you drink doesn't make much difference. There are antibiotics, don't die before you can get some.
"badly blistered feet": The right footwear is EVERYTHING when going on a difficult hike. #2 is turning around early if one has the wrong footwear.