What "Uzumaki" techniques does Naruto have ? :| He has no seals whatsoever, the jutsu in which Uzumaki's were meant to be proficient in...
To be honest, I think both you and the people who think the other reason are right. I think the sage will look like a red-haired Naruto. I mean, why not show his face if the problem is the hair?
You know what would be an awe full troll on Kishimoto's part? If the sage has the same face as Madara.=D
nice analysis!