I'm pretty sure that Receiver of Wrecks doesn't apply to protected sites... just your average, run of the mill wreck. Down here in Nova Scotia I guess the deal is: you hand your artifact over, and they hold it for 1 year. If the owner of the wreck, probably an insurance company wants it, they have to pay you a salvage fee for the item. We have wrecks here like the SS Atlantic that are protected sites and it is forbidden to remove anything from them at any time, even if you intend to turn it over to the museum.
He recovered his items before the Empress was protected, so he followed the rules at the time, but you couldn't do that now..... but like I said I'm not sure if that protected status would void a former legal procedure, it might depend if the holder of the item were the original salvor, or a new owner.
Salvage of small items from the older flattened out wrecks down here is not generally frowned upon, depending on the boat you're diving from. It's much different than the beautiful, preserved wrecks you have in Ontario... we've pretty much got debris fields here. But that's a debate on it's own.
chris