Unlikely that they would be finding clay that high up, downstream on the mountains would be far more likely. I know people who have done pottery with naturally harvested clay, and its intensive and wet work, in those conditions you'd loose far more calories to heat than you'd gain from hunting. Better off to always be looking for smooth stones, and trying to get close to game.
As for the "pros" being asked to do it, I don't think that would have been part of what the producers of the show wanted. Les has said that the survivor man shows took a toll on his body, even though they were only a week at a time, his nutrition and dehydration were hard on him. As for Cody and Ray, even Bear or Dave, I don't really think the show in its competitive nature is really their style of doing things. For most of these guys it is about what they can either learn or teach, so what would be to gain? Not to harsh on the thought experiment, but what would they have to prove? That any accident that can take out a regular human can take them out as well? Sure a "failure" would be a damage to their brand, which they have to think about to maintain a living. And why risk that when the scorecard is in someone else's hand? All negative with no positive for them to try it.
Tough luck for Dave, but I don't think it would have mattered if he'd left the bow strung. If he couldn't string it, he wouldn't have been able to effectively pull it. I think they made the right call to pull him out, based on his responses, he wasn't thinking clearly anymore. Even though they showed him talking about eating more of the fish, he left it too late. With a BP that low, and that percentage of his weight gone, he was in a very bad way. Props to him for going as long as he did, and showing what is possible. Deciding how much effort to spend on each method of getting food is really the crux of it. Its largely down to luck, and tapping into a resource that works for you. I'd honestly spend too much time actively fishing, because that's my mindset, I fish, and neglect other things.