I would definitely try this. Might be a bit gimmicky, but would certainly draw attention from the general public to a display area. I would have to be convinced of the stability. Does the tree need perfect radial symmetry for balance? Or to be of much less mass than the magnet?
Probably the only way to answer these questions would be to get one yourself, and try, or to ask someone who has one. Good questions though.
Yep, I agree, Avatar references are passe, trite, pop culture has moved on. The point was not the movie reference, but that more than once displays were done with attempts to make the bonsai look like it was floating disconnected to the display stage. Acrylic, and very thin wire stands have been used with this effect in mind. So the idea of "bonsai visually appearing to float" is not a new idea. Now there is another way to pull it off.
Hey, the bonsai world has already been treated to a Larch in 1929 Hoover Vacuum, at what was billed as the "Most Significant Artistic Bonsai Show to Date in the USA", the Artist Cup. There also is the example of the Show organized by Robert Stevens in Indonesia, which included performance pieces with live dancers moving through the art & bonsai installations. And at that show also featured one display with a photo of Robert himself, sitting on a toilet, contemplating a bonsai. I guess levitated bonsai would be more trite than controversial.
IF the tree were well done, it could be put in a show. Definitely not the craziest display idea out there.