Well unless the 501st commits to an actual definition of what recasting actually is, instead of the ambiguous definition that exists, which I might add is going to ruffle some feathers regardless, you really can't fairly police it and as the rules state its not your or the legion's job to do so.
Plus, if you look at it from a certain point of view, the 501st will always be condoning recasting as long as they allow members to be admitted with recasted armor. Granted thats the extremist point of view, which I don't share mind you, but I'm sure theres someone out there that would think that. Imaging trying to check every submission's armor for caster pedigree. YUCK.