Sure, it matters what is meant by "salvage." To raise the ship, even just to tow it to shallower waters as in the case of Ehime Maru, is a tens-of-millions proposition. To simply dive on the wreck and recover human remains and other valuables from accessible areas is still at least another zero beyond $40,000. I have no problem with a company doing something pro bono. But why such a pittance? Why just not donate the entire effort for free?
If someone offers you a brand new Mercedes for $1, you're likely to think there's some sort of catch. It's not a credible offer, if everything's on the level. Therefore if you're unable to discover what the catch might be, the safe bet is to reject the offer in case you might be embroiled in something you didn't intend. While that's the safe bet, you're still vulnerable to criticism like, "Hey, that guy passed up a $1 luxury car!"
And unnamed "Norwegian dive company" collaborated with Evertsson on his film. Coincidentally there's an unnamed "Norwegian dive company" offering a salvage deal that's simply too good to pass up -- a $1 Mercedes of an offer. One wonders whether the offer was tendered for no reason other than to create suspicion when it was naturally rejected. "They passed up a killer deal to have the wreck salvaged; there must be something nefarious going on."