Right. Denzinger is not the Magisterium. One could argue with the weight to be given to Innocent III's view and say it's his "opinion." However, its being deemed worthy of an inclusion in Denzinger certainly makes the "opinion" one a Catholic could certainly hold to and entertain, and one would not be "fumbling and bumbling," theologically speaking, by agreeing with Innocent III on that point - to put it mildly.
Lots of stuff is "included in Denzinger" that probably shouldn't be there, especially after the Rahner edition. As I've repeatedly said, the Augustinian position that infants who die without Baptism suffer (albeit mildly) in Hell has not been condemned, and therefore it's tenable, though one could probably count on one hand the theologians who held it after St. Robert Bellarmine. My reference to "fumbling and bumbling" was in the contradictions made by a poster above often from one post to the next. I think the that opinion is completely wrong and that St. Thomas was right ... but you're entitled to hold it. I also think Molinism is wrong, but the Church has ruled that people are entitled to hold it without condemnation.