If you have knowledge of any newly uncovered issues re COE/CTE between aluminium and brass please do share it with us.
No _new_ issues, only those that have existed for all time.
In the Navy, you learn to never tolerate iron/aluminum direct contact joints because of electrolysis.
I do not know what Al alloy is specifically used in these composite bottles, but the boundary interactions between the metals used in the bottle and the regulator would appear to be a real target for the investigators in this case. This despite the fact that they may have been standard practice for some time. This was not an exploding bottle ( my guess). This was a bottle whose regulator popped out in a real hurry. I am not addressing the walls of the bottle, but the brass/aluminum interface. If the bottle could ever be found at the bottom of the sea, I suspect it would be mostly intact with some superficial external damage.