By your logic, any random long-urbanized space on Earth should remain untouched because at some point it was the site of people's (often violent) deaths. These

By your logic, any random long-urbanized space on Earth should remain untouched because at some point it was the site of people's (often violent) deaths. These ships weren't memorial vessels, they were just ships doing work and there's nothing wrong with salvaging them. Cemeteries are a different story. They represent places where people specifically chose to bury their dead for the sake of memorializing them.