Board Thread:Off Topic/@comment-25121612-20130804234437/@comment-6881629-20130805091744

Yep it was a quest from the Arch-Mage (he was a little nuts) i think it was possable to replace him as Arch-Mage before that quest as if you did the quest Kill the Telvanni Councilors too early the main quest would be broken (and i did almost all the faction quest before the main one).

Also not everything in a game that you can do is cannon you can only really be sure about the main quest.