I misinterpreted your point due to my own misunderstanding of quantum spin, a subject I'm currently studying. I see your point now, due to the dipole nature of magnetism, and the confusion came from the original "so you could not do the same for a human," in which I think you meant "you could not do the same in a perfectly uniform field."
You could not do it to a human because you'd need a nonuniform field over a much larger distance, which means the maximum of that field would have to be enormous, far higher than in the frog case, and far higher than could be generated by any practical electromagnet, superconducting or otherwise.
