There are entire books dedicated to the topic of Naive Architecture ( sometimes referred to as Outsider Architecture. )
Among the most famous examples are Rodia's Towers ( aka the Watts Towers ) and the Coral Castle.
The very least our treehouse designer deserves is immortalization as an architect.
I move to add it to the National Register of Historic Places. That way the park can't tear it down. Sure, it seems awful soon to declare it of historical value. But given his AoA, we must act fast before this house becomes too old to interest its creator.