Investigation fairly easy?
You're at 100 feet. Your gas is ticking down. You're in "0" visibility. There is a 5 knot current. The fuselage sections are relatively intact and filled with bodies, luggage, seats, narrow aisles and all the miles of wiring that are in a plane.
What do you consider challenging and dangerous?
UMMM.... Looking at that video and basing my opinions on what I can see, It is NOT "0" viz, nor is there a 5 knot current. 100fsw is NOT deep, especially considering that most of these "At Sea" crashes take place in water that is not diveable. I wouldn't worry to much about my gas ticking down considering I could easily run a 60 minute bottom time and still deco out on backgas.
Consider that aviation investigations are pretty freaking tough to do when you cant find the aircraft, or when you only find minor debris. In this case, there is potentially an entire aircraft that can be recovered, and bodies to return to families....It sounds bad to say that its a "Good" scenario, but in reality it is an accident investigators wet dream.
What do I consider Challenging and dangerous???? If the wreckage wasn't in recreational depths, actually had 0 viz, and was patrolled by megalodon sharks.