Good luck healing your leg!
Thanks for the info. While I'd like to speculate wildly, I feel I owe it to people to read more of this thread first. Not sure I'm up for the slog. Anyway, my thinking is the most likely happening is Bill got lost (anywhere west of the Stubbe Spring - Quail Mountain line), and was uninjured and alive until exposure got him. What's surprising is that a healthy avid desert hiker doesn't pop out of that wilderness within a week or just days. Ten "crow flies" miles in most directions from Juniper Flats puts him on a paved road or in a backyard, likely with city glow for guidance at night.
If he really carried only 24oz water, that suggests he planned something like - over drink at the car, jog to Juniper Flats, summit Quail and return to car in 3+ hours a little thirsty. Going light on water suggests going light on all else too. Maybe sneakers instead of boots, no map, no compass, no 10 essentials, maybe no pack, etc. Maybe a favorite pocket knife (though TSA probably took it), but otherwise no survival gear but wits. I would do this, though I might carry a bit more water if I used a pack. Once lost and evening comes, if he's got his wits, he'll be thinking GF will report him missing, and rescue will looking for him the next day. I think chollas are a PITA, and would tend not to hike at night unless I wore boots. It's not cold enough to be dangerous. The heat is probably manageable. So mostly stay put until rescue comes or put minor effort into finding the trail or water. Try any desert survival tricks he's heard - move only at night, cactus or yucca for water/food, sand burial for heat protection, drink pee, catch a lizard/snake/bug, etc. Climb a high point and try the phone (does he know to leave it on to send a text?). 3-blast the whistle if he has one. Smoky fire if he has a lighter. Check (or dig) a low point or canyon-side for water (any geology background?). Were there T-storms in prior week? Does he eat the Mormon Tea? Intentionally or unaware, that could give surprising endurance.
By Saturday morning (or evening) there's no sign of rescue. Now he's gonna self-rescue. We think he looked at maps, so even if he doesn't carry one, he may know downhill leads to safety. He may also know his boundaries - the park road, CA62, I10, and maybe that southeast is a bad direction. Without the cell phone ping (and not visiting the area), I'd look in the drainage southwest of Juniper Flat (also drains Stubbe Spring), or maybe the East Deception Canyon drainage (especially if i believe the 10 mile ping). With the cellphone ping, it's harder to argue where Bill pinged from without finding the Covington Flats. And why if he found the Covingtons, he wasn't found. Washes have no water and no shade, so that would be a reason to try a canyon instead. Although if there were people in the Covingtons, seems hard to make a 10-mile cellphone ping from that area and not see a car there (unless he passed through at night, or couldn't see distance).
I see Tom thinks steep sand makes slow travel. If one lets go of firm footing and embraces the dirt glissade, this terrain can make for fast fun easy travel.
That's my thoughts as someone who likes to hike, has been disoriented a few times, seen others confused at obvious spots (at a junction with trail signs and GPS and map and compass), and has hiked/backpacked in deserts. As an internet snipe hunter here who's never been in this specific area, I expect my insights lead you to Bill tomorrow
. Probably I just speculated what's already been said 10 times in this thread
Thanks for keeping the thread up.