Interesting article, however if you read about the horrific accident that killed a friend of mine, Sam White near Richmond VA a few years ago, you know that a significant amount of black powder in that 9" Dahlgren shell was still live and ready to explode. I don't want to repeat the gory details but articles at the time got into some detail on the force of that explosion, and in my humble opinion, there was a lot more "energetic material" involved that a few cc's of mixed gases, no matter what kind of gases they were. The article discounts any contribution from the old black powder, which is wrong.
When I was younger and more foolish, I deactivated some larger, excavated CW shells myself. When the powder was ignited later to get rid of it, it still had lots of energy and burned very rapidly. These were Confederate 8" spherical shells, many of which were found around old gun batteries in the outskirts of Charleston, SC.
The article mentions a Parrott shell that blew up when Lars Curley tried to disarm it; that was mine, the one I mentioned earlier.