"what's the status of limitations on grand theft? pretty sure it's less than 100+ years..."
Sure, but what is the expiration date of laws, acts of government or treaties?
There is none.
They are in force until specifically repealed.
And that is the problem for those who want to get rid of committments to the Indians.
A treaty is the Supreme Law of the Land according to the US Constitution. It's still in force, and so are the treaties concluded under it.
Likewise for Acts of Congress, or even of state legislatures that recognize tribes.
I haven't much looked into the Shinnecocks, because it's pretty obvious to me what's going on out there, but so long as there was an act of government that recognized them, they'll win. That's the way it works.
Close the reservations. Just about any ethnic group can make a claim based on ancient history that they've been abused or swindled out of something. The reservations should be closed and the land sold over to development. Of, course the indians should be compensated, but not given special rights to sit on huge tracts of land and special privileges. Live on the suburban reservation like the rest of us.