Okay, so the Property Clause has been interpreted as allowing the US government the right to own property. Napolitano didn't say it didn't.
Regardless, the point is that the Property Clause in this article is being read and interpreted in the absence of the Enclave Clause, concerning which Napolitano was undoubtedly also referring.
Here's the most interesting thing about this whole "debate": The Treaty of Guadalupe Hidalgo, which I knew was going to come up sooner or later. I heard Thom Hartmann mention it in passing, but I didn't have time to address it at the time.
Here's the deal about that "Treaty." It is based upon an illegal war wage by the United States against Mexico.
Have you ever read about the origins of the Mexican-American War? Have you ever heard of "Mr. Polk's War" and the Spot Resolutions by Abraham Lincoln?
The upshot is that Lincoln believed that President Polk trumped up a false-flag attack that not only was false but may not have happened at all. Lincoln demanded that the President show the exact spot where the Mexicans attacked American troops. That information was never forthcoming to my understanding. Lincoln believed that the whole war effort was about violent Empire building and land grabbing. From what I've read, Lincoln's position seems the more plausible.
If it is, and I think it's highly likely, then the US truly didn't legally come into possession of the land in the first place.
Even if it did though, reading the Property Clause in light of the Enclave Clause and reading it without bending it to fit the desire to building and holding illegally, immorally, unethically gained Empire, leads one to believe that, in deed, the federal government shouldn't have held onto the land but should have started from the position that all lands within the bounds of the given incoming state are not federal but that the federal government would purchase a rather limited amount of land from the incoming state for the express, limited purposes mentioned in the Enclave Clause.
It doesn't due to say that the US had territories that it allowed to become states under the condition that the states agree in advance and write it into their state constitutions that the federal government would retain large swathes and land (81% in the case of Nevada).
So, I may not deem PolitiFact's "pants on fire," but do deem PolitiFact ignorant in this case. Check again, PolitiFact.
Don't just say that the Supreme Court said or experts say. Look for the truth. The Supreme Court doesn't always tell it and neither do your "experts."
By the way, my take won't be at all popular with the Libertarians, who generally despise Abraham Lincoln, even when Lincoln was right.