Given the proximity of the rigs to the So Cal shore, time of day, his exposure protection and an almost full tank (less 15 minutes) of air, the heavy boat traffic in that area, and the resources available to look for him, I think imminent death at sea was not exactly his only option. I would have been pissed, but I don't think (and hopefully will never know for sure) that I would have been making my peace with the universe until closer to sundown.
That's a good point... I don't know the area well. And also, even though they were looking for him in the wrong place, Dan would have had no way of knowing that, and probably assumed that they were looking for him in the right place while he was drifting!
Still, I might not have been so sure of a rescue in that situation, given the fog and the current. I wonder if there is a map anywhere online showing the two dive sites and his drift line.. I googled a bit, but couldn't find one. That might help us out-of-towners understand the situation better...