Even if FIFA decide that Oxford is a higher Category club than Columbus, it seems like an overly complicated arrangement that, as well as raising the interests of the tax man both sides of the Atlantic, is a pretty speculative deal for Columbus.
Surely they could use that money (and space in their salary capped roster) to bring in a player that would actually play for them and that they could trade later for future MLS rights.
I don't see how this loan arrangement would be better for them.