I just read an article that said the explosion in the sub would immediately incinerate all the bodies.
https://www.bbc.com/news/world-us-canada-65934887
When a submarine hull collapses, it moves inward at about 2,200 fps. The time required for complete collapse is about one millisecond. A human brain responds instinctually to a stimulus at about 25 milliseconds. Human rational response - from sensing to acting - is believed to be at best 150 milliseconds.I could see Navy submarines having some hydrocarbon vapors, but a "high concentration"? Submariners could not breathe air with a high concentration. I doubt that there were any combustible hydrocarbons on the "Titan," either (unless you count the human body as a "combustible hydrocarbon").The air inside a [I presume Naval] sub has a fairly high concentration of hydrocarbon vapors. When the hull collapses, the air auto-ignites and an explosion follows the initial rapid implosion. Human bodies incinerate and are turned to ash and dust instantly.
But the rapid compression and instantaneous temperature rise to hundreds of degrees C might auto-ignite the human body. But the human body has such a high water concentration that it would need to desiccate before it could ignite. I doubt the body would have enough time to desiccate and auto-ignite before being quenched by the water.
The other difference between a Naval submarine and the "Titan" is the former is made from somewhat ductile metals whereas the Titan's hull was made from brittle carbon fiber. I expect that cause a completely different failure mode than a metal submarine hull.
It's an interesting (but ghoulish) exercise to think about from an engineering perspective and conjecture what happened in the final few milliseconds.