Territory here refers to land in the possession of the United States, not "territories," the administrative divisions later set up by Congress on its Territory.
The state of OH was admitted in 1804, I believe. The vast majority of its land was at the time public domain land. Congress did not turn over that land to the new state. It allocated 5% of the proceeds of the sale of that land by the United States to individuals to Ohio, but required the state to spend the money on roads.
When other states were admitted, they generally followed this precedent, without exception I've seen. Land that hadn't been sold by the feds prior to statehood remained as property of the federal government until it was sold.
The problem is that in much of the West, primarily for location and water reasons, nobody bought the land.
Some of it was withdrawn from potential sale starting in the late 1800s to form what eventually became the National Forest System. Most of the rest was eventually administered by the BLM, but was largely still available for sale till the 50s or 70s.
The Constitution gives complete power over property owned by the United States to Congress, which can pass a law to grant it to state ownership. Or not, as it chooses.
But there simply is no constitutional issue here.
Whether Congress uses its power wisely is of course a separate question entirely.
Well, it looks like we’re talking about precedent, rather than Constitutional interpretation, here. But in times past, nobody thought of the federal government as the threat it is today, so I’m not sure this issue was ever contested on Constitutional grounds.
I find your interpretation of what a “Territory” is hard to swallow. According to your interpretation, “Territory” could mean any land with a State not previously held. I don’t believe a state or land within a state is a “Territory.” The traditional use of the word “Territory” is United States’ land that is not a State. It looks like the feds sold the “public domain” land states to individuals in the Ohio case and afterwards. At the time there was probably no objection so probably no one raised an issue. But I see no constitutional justification for doing so, unless it was part of the deal the feds made with the state.
Even if it was part of the agreement for a state to become a state, unless the state or the people allowed the transactions to take place they way they did, again, there is no constitutional authority for the feds to do so. I would say that in the initial transfer of a territory into a state, the Constitution gives the feds power to negotiate the initial agreement. But after a certain point in time after the initial transfer and creation of a state, I see nothing in the Constitution that allows the feds to hold onto land within a state without constitutional justification, historical record notwithstanding.
Probably time to revisit the whole issue and clarify state’s rights vs. federal power regarding lands within a state because now there is an issue and ANYTHING the federal government does is a constitutional issue.