Y'know he might just be young, though I doubt Mage Society really allows for rapid upwards mobility, but I gotta say, Sage Dude, from what little we have seen, seems to have really Young Features. Young Features on a character that would stereotypically be quite old. Young Features on a plausibly old character in the same chapter where we got some explicit mentions of Witches using Magic and Human Experimentation to achieve Immortality.
I'm Jus' Sayin'....
Also yeah there's probably Good and Bad Apples in every Sect. So far, the only truly unifying trait possessed by all of the Sects the Pointed Hats have wiped out has been an implied or explicit rejection of Pointed Hat Authority.
Again, Jus' Sayin....