If he did go back in (do we know that for sure) 3 times (why when there were only 2 others in it).
First time to activate the float switch. Second time after the aircraft settled under the floats, to look for the others, unsuccessfully. When he surfaced second time, one of them was up. Third time to look once more, he saw an arm, yanked on it and out came the third. No doubt beneath your standards, you would probably have only needed one breath of air to save both pax, the iPad, the logbook and the fuel receipts.
It's worth noticing that the second person to surface did so by himself, but was the one who needed CPR just minutes later. Exhaustion, hypothermia, previous conditions perhaps. It ain't over till it's over.