RIP Gregory & condolences to Mills family. It's really unfortunate situation.
I have been to WaKaToBi dive resort. Most of the dive sites were easy dives. They have a good safety minded operation too. It is indeed a good resort to be for beginner divers. Hopefully more detail incident report comes out to better understand what made him panic.
This diver panic underwater remind me of this incident:
Dang, that's scary to watch.