Hmmmmm….
I think I would most definitely have erred on the side of caution and followed decades of traditional magnesium painting processes, instead of trailblazing a new approach because of your painter’s product preferences.
I am sure the wheels will look just fine upon finishing with the non-traditional painting process.
Obviously, the question of whether your painter’s approach will provide ….long-term…. paint adhesion is one that will not be immediately revealed.
Larry