The comment you link doesn't even remotely state it's impossible though. Mostly, that you won't have the same tree up there than you natively have on the ground. Which is kind-of obvious really, especially if "on the ground" is flat lowlands.
It goes further than that: air near the surface of the earth is doing a lot more interacting with the earth than the other air, and is getting and keeping a lot more heat and dissolved gases. That includes air at sea-level or air at a mountaintop. Thus, there is no natural analogy to a tree growing atop a 500 foot building. Even bristlecones at 10000 feet still benefit from air that has been in prolonged proximity to a surface.
