There was no misinterpreting here on my part
Selective interpretation then. You're big on explicit, well Article I, Section 8 explicitly says "all places purchased by the consent of the legislature of the state in which the same shall be..." The intent of that if obvious; property obtained from the states is the sole and exclusive responsibility of the federal government. There is no shared ownership or divided authority over it. But the land in Oregon that we're talking about was not obtained through the consent of the state legislature. No such consent was needed because the property was never owned by the states, and the legislature never had authority over it. Such property, as Article IV, Section 3 states, was the property of the federal government before the state as created and remained the property after the state was admitted. Only Congress could dispose of it, and only Congress, or its designated agents, can make any rules or regulations impacting it.