Another argument: in future, scientists will be able to chart every particle of mud and every molecule adhering to the potsherds. Taking them now, by even the most meticulous and 'responsible' methods, prevent future archaeologists from scanning them properly Star-Trek fashion. So today's 'scientists' will be viewed as pot-hunters in the future.
I say, do what you can with what you have now. Because ultimately you should do nothing, against the day you could do better.
This seems like a clear case of letting the best be the enemy of the good: had the shipwreck not been salvaged, looters would have destroyed everything.
And how the heck can a scientist claim in good faith that there is knowledge people shouldn't be allowed to see?
I wonder how much the depth of the wreck should play a role in deciding how these wrecks are treated.
At 40m or less, wrecks can be explored using recreational scuba gear. Every effort should be made to catalog these wrecks and remove all items of any interest before recreational divers are allowed to visit the site.
Down to about 200m, tech diving equipment can still be used, but the danger and the skill level needed to salvage goes up. Given the likelihood that the wreck will be unexplored by any other than professional salvagers, the archeological rigor with which the site is treated should go down. Proper archeological treatment of the site will mean more dives and an increased chance that someone dies. And the equipment is quite a bit more expensive. It's only natural that they'd limit themselves to the more profitable salvage and leave what is essentially charitable salvage to any organization that can solicit enough donations to do their own work.
Below 200m, you're talking submersibles and robots and the cost to salvage goes way up. Expecting archeological rigor at those depths likely means that most wrecks will be completely unexplored. I'd rather see the valuable stuff salvaged and put in museums than just left on the ocean floor.
But perhaps I'm being too myopic to my own interests and those of other scuba divers.
People are going to salvage shipwrecks if they contain something valuable. The end game of this kind of thinking is it becomes illegal unless you have some sort of credential, and people who find shipwrecks take priceless artifacts made of gold or silver and melt them down for sale, then don't tell anyone about the wreck.
I say, do what you can with what you have now. Because ultimately you should do nothing, against the day you could do better.