While it is possible that they threw in a ringer, I doubt it. Its not needed, and why have him bail out so early?
I honestly think he got into his own head on that one, and didn't have a squadmate to take him out of it. He was bucking wood into nice little blocks, thats a guy who's on autopilot, not someone planning his moves. He freaked out and tried hanging a bear bag with the only line he thought he had, 40lb test mono. But it looked like he was trying to hang more than 5lb of gear. Even then, taking knots into account, its not that hard to see that he was at a disadvantage. As I said last season, Fear does weird things in people's heads. Its skills plus mindset that will get people through. He may very well have the skills, just didn't get to show it.
From what I understand, red tide will be resident in the shell fish for a period of time after the water is clear, so I would bet that they have some indicator that it will be safe to eat. A standard slow taste test (skin, lips, tongue, consume) should let you know it was safe, I'd think. Its a neurotoxin, so you should get tingling if you taste it. But that's just my guess. If part of the way through they can start eating the shellfish, that could really push some change, and if they know that that they just have to make it 10-14 days say, then that could really help the mental state.