I think Vatican II gave him permission ...
Christ summons the Church to continual reformation as she sojourns here on earth. The Church is always in need of this, in so far as she is an institution of men here on earth. Thus if, in various times and circumstances, there have been deficiencies in moral conduct or in church discipline, or even in the way that church teaching has been formulated-to be carefully distinguished from the deposit of faith itself-these can and should be set right at the opportune moment. (Unitatis Redintegratio, §6)
Trust you to know the quote! ;)
Me, thee, and he, don't have authority to contend against the MAgisterium.