firstly few councils were ever held in the city of Rome.
secondly canon was certainly discussed at councils though indeed no specific canon of any specific council declares what is definitlvly IN the Bible though many declared what was right out for sure.
further while athansius opinion is certainly important and relevant I don't see any reason for taking it in a vaccum; all decisions should be made as the whole church not simply as individuals; far to big of a risk there if you ask me.
I think if you wanted to read my posts carefully I never stated his decision was made in a vacuum or accepted in a vacuum.