If it really happened the way he says it did (implosion at 3,500 ft when they were travelling down to 13,000 ft) this sub was in no shape or form suited for this dive.
It's not confirmed at this point as I understand and Cameron also disclosed it as a rumor in a recent interview on Youtube.
Just read about Stockton Rush's (CEO and "pilot" of the sub, presumed dead) views about security:
https://en.wikipedia.org/wiki/Stockton_Rush
It's just amazing how an aircraft pilot, a guy with an ivy-league degree in aerospace engineering can have such twisted ideas about standards, regulations, and security in general.
No way in hell would I have signed up for this haphazard dive.
Lol quite poetic indeed: Titanic was considered to be "unsinkable" and OceanGate's CEO said "security is a waste".
They both got a hard reality check from nature and physics.