User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-1685631-20130403194355

Well, after some more Unite Silver Rathalos runs, I've noticed that his eyes are actually pink. I've come to the conclusion that he is in fact just an albino Rathalos, forced to retreat to a more secluded area due to the loss of camoflauge.

I would then posit that Gold Rathian is a genetic mutation along the same lines, and faces the same situation as Silver Rathalos. Therefore, they're technically not subs at all, just extremely rare genetic mutations.