so? You don't know why he was using that reg. Sponsored, borrowed, already happened to own? All much more likely reasons than choosing that specific one for that dive....
Apeks is one of the few manufacturers who have heavier duty ANSTI equipment to test the performance of their regulators to very high depths and extreme cold water temperatures. That follows through into the performance of their products at depth and in cold water environments.
From that perspective, if I was silly enough to try going very deep, I would choose an Apeks regulator.