It irks me when "experts" use language in non-nonsensical hyperbolic ways.
It takes much longer for a vehicle at the depth mentioned than two nano-seconds, and much, much longer than four nanoseconds for the event to register to your brain.
Consider, realistically, how long it would take the submersible to implode. The pressure outside was about 6000 psi greater than inside the submersible.
The submersible was about 7 feet across inside. Assume the walls have to move in only 18 inches to kill everyone. Starting from zero, at about 20,000 psi, a bullet takes about 2.3 milliseconds to accelerate and exit an 18 inch barrel. The pressure is still above 6000 psi when the bullet leaves the barrel. Higher initial pressure, unidirectional, 18 inches travel 2.3 milliseconds. The implosion will take longer.
2.3 milliseconds is 2.3 million nanoseconds.
Nerve impulses move, at the most, at 400 feet per second. Assume minimum length of sensor to brain of 1/3 foot, then the impulse would take 1/1200 of a second, or .833 milliseconds. Perception takes much longer than mere transmission. Images have to be processed, as do all nerve impulses. Perception, as measured by reaction, takes much longer, on average 200 milliseconds.
200 milliseconds is 200 million nanoseconds.
Ok Einstein, so how many angels can dance on the head of a pin?
It’s over before before you feel it...like stubbing your toe and the slight lag before the swearing starts.