We really don't care. Anything short of land back is genocide so we are going to fight against the reaction. The Americans are not ready to feel the frontiers again and the frontiers are ready to fight back. The US military collapses if the Black, Latino, and indigenous soldiers mutiny. I've pointed out that Americans occupy less than 25% of the lower 48. Winnable odds, much more winnable than any existing attempts of radicalizing the white workers. This country runs on us.

If population means share of land then we might as well give a fifth of the world to China.

And the Americans still benefit from settler colonialism. I pointed out Alaskan drilling and the hydro-electric battery being built on Yakama land against the tribe's wishes. Homesteading ended in the 70s and the American landlord class is made of those settlers who got free land. Americans as a people do not need or intend to live on a vast majority of the lands they own, we are taking them back.

You are in effect making the argument that their interest is best served by holding on to all of the land since that enables their system to continue.

If this was the case then what the hell would we all be doing on anti-Imperialism forums? The Americans do benefit from colonialism and imperialism. The contradictions with their Bourgeoisie are being hidden through the consumption granted by the empire. Even if the systems of oppression benefit settlers, they don't have any freedom to meet human needs. If they are content with finishing our genocide rather than working towards internationalism then let them be consumed by history.