I think it works like insurance - replacement value.
They could just pull up stakes and start anew. I mentioned a nice little one in mine-friendly Wyoming. Here's another one in more or less mining-friendly Australia - At least the Australian government wouldn't try to rip them off.
The Jungle Well Rare Earth Project is located 80km west of Leonora and was recognised for its REE potential however no analysis was carried out during a late 1990’s diamond exploration program. During 2007 a trench sampling programme identified significant RE values from an exposed dyke of 6.9% and 8% REE.
That's like bonanza grades. It's a typical exploration level jr. with like a billion shares @ 0.01 a share. It's just one of their projects. I bet they might let it go for a few million. Stans would still have plenty left over for studies, development, construction and equipment.