Probably the tube collapsed and the end caps were slammed together.

The problem with water being basically un compressible is it would not have occurred exactly evenly over their body like it would have if they were already in the water VS a pocket of air, the walls closing in at thousand miles an hour (Hyperbole as I don't know the exact speed but rest assured it was extremely fast and certainly over mock 1) would have smashed them into oblivion, probably from the center of the tube where the collapse probably started and forcing them into the titanium ends that appear to have not been significantly damaged, the exact damage done to certain individuals probably depended on who was sitting exactly where... my guess is stockton was sitting in the window and driving it and likely to find bits and pieces of him or whoever was in the opposite end, since there was no window in the opposite end the individual closest to that end is the most likely to find bits of them. The heat probably caused some charing on the surface but they were not totally incenerated or turned to steam because there would not have been nearly enough oxygen to combust all the HCs (A/F ratio was waaay to rich) and boil all the water in their body fast enough before the increasing pressure held it from vaporizing, the higher heat from compression could not heat it enough to vaporize the water in their body as the increasing pressure was working to keep the water a liquid ( also think about a steak when you cook it if the heat is way too high it can burn the outside but the inside is still cold and how at lower elevation water needs to be hotter to boil because of higher atmospheric pressure), I suspect most of the damage to their bodies and what killed them was from 5000+ PSI pressure differential unevenly squashing them.

Also there ARE significant ocean currents at the Titanic, it has caused problems in the past with the live broadcast from the russian sub 20 years ago for example getting stuck in the Titanic for an hour or so before getting free. It had to be NEAR (but not ON) the bottom or the stuff would have been spread all over the Atlantic and I have not seen any carbon fibre in the pics so it probably shattered into tiny bits and was washed away by those currents since it is much lighter than steel, titanium or other stuff the ship was made of and the way it shatters the particles would have easily drifted away had it been ON the ocean floor.