Although I am not sure I agree that IWR is a last ditch effort, I do think that his decision to have only O2 on the boat was likely not to delay transport of the first victim. In fact, I immediately wondered if his decision to surface was not for that reason. A boat captain has a real problem when it is necessary to transport a DCS victim as soon as possible, but there is another diver doing an hour of deco below.
A similar situation happened in Cozumel a while ago. Three divers, including the owner of the shop, did a dive intended for 300 feet on AL tanks, but it ended up going to 400 feet. They eventually surfaced having done no deco. They needed to get to the chamber as soon as possible. Unfortunately, they had chosen to do this dive off of a boat doing a regular dive with customers, and the captain refused to leave the divers who were still below completing their dives. The shop owner did not live, and one of the others will never walk again.