That diver did not have the ship sneak up on him, he was diving in a shipping channel and knew there would be a ship coming up. He prepared by staying next to the large chain on the bottom and holding onto it so he would not be sucked into the propeller. In addition, the reason the ship did not sound "loud" to you is the way gopro records audio. Had this been recorded with a calibrated hydrophone the noise would have been off the charts.

I agree with you the bigger problem is sonar but I hold my opinion the whale in the video swims how it does because it is avoiding the sound of these ships, it is not acting on sight or attracted to wakes/ plankton.