IIRC this case involved State border definition. Since the border is a river, it is constantly being reshaped and property lines become fluid, pardon the pun.
If indeed your supposition were the case, then the matter would be one to be settled between the two neighboring states. Involvement by the BLM seems both unnecessary and intrusive.
To say nothing of the apparent greed.
Let the States duke it out. If the land is privately owned, I would think it still belongs to the owner regardless of which State it supposedly is in. If a State thinks it can legally grab someone’s land, they should at least be required to compensate the owner.