Does it sounds like the property owner has no rights and no compensation?
That’s the rules over there.
The article isn't very well written, but under the Treasure Act of 1996, it all belongs to the landowner. Usually the metal detectorist asks permission and they make a deal like a 50/50 split. This guy, however, didn't make any such deal it seems, so the landowner gets it all. Then an independent board of experts sets a fair market value. Museums get first refusal at that price. If no museum is willing to pay, the owner can sell them on the open market.
It might sound that way, but it is not the case. The compensation is quite honestly very fair.
In fact, I would guess that, apart from their historical and academic interest, these things are probably not all that valuable. There might be a lot of coins but they are base metal and not in particularly good condition either.