We only know 2 things for sure. This man died shortly after surfacing and we do not have all the information.
A proper autopsy could tell you if there was heart attack, if the clot was still there and big enough to see. The only thing that the water in his lungs tells us is that he was breathing when he hit the water after falling. If he got shot and fell off the boat he would very likely have water in this lungs, so that really gives us little information. There are alot of medical problems that could stop your heart and not leave any kind of trace at autopsy. I have never observed an autopsy where DCS was a factor so I can not comment if DCS would be evidnet during a post, but I suspect it would be hard to detect.
We need the rest of the medical information and a detailed dive profile from someone who was actually there to make an accurate determination. My gut feeling is that this was a medical problem, not DCS. However, that is speculation on my part.
From the sounds of it from the divers that have actually done this dive, it is a well controlled dive within the tables. As we all know, that does not mean you can't get bent doing it, but unless there is some evidence to the contrary that he was off the tables, I do not think it was DCS.
Having said that, I am the first to admit there is not enough informtion to tell for sure.
As far as "recreational limits" go, what are they? Some say nothing deeper than 60ft without advanced OW or deep training, back in the day it was 100ft for OW, and now 130 seems to be the "official" limit for rec diving. There is just no "hard" rule so I don't think being 8 feet past 130 killed this guy.
One thing that bothers me is that they only tried CPR for 14 minutes in a witnessed arrest. That seems like throwing in the towel a little soon. There is a guy in my town that is really happy I did CPR on him longer than that, and he was down 7 minutes before I got there and got started. We worked him 35 minutes before we got a pulse back, and he was back to work 8 days latter. With a few broken ribs, but he forgave us for that.