But I think what actually happened was someone somewhere else in the Canadian gov't saw a news interview and told SpaceX.
The space law experts I talked to agreed that since SpaceX has now asked for it (assuming it *is* SpaceX), the farmer has to surrender it. BUT he should ask for compensation.
If there had been damage, the US gov't would have had to compensate the Canadian gov't, but because it's a private company, and no damage happened, compensation is voluntary