Glad you asked. Here's where you're wrong. Doctrine is determined by Scripture and Tradition-with-a-capital-T, which means "What the Church has consistently taught."
As for Scripture, that is Public Revelation and that ceased with the death of the last Apostle, approx. 100 AD.
As for Big "T" Tradition (Sacred Tradition, not just local, temporary, or customary stuff like "Green is the liturgical color for the Sundays in Ordinary Time"), the Nicene Creed is a good example of Tradition, and as you will see, it is an authoritative interpretation of Scripture. The Trinity, The Incarnation and so forth.
A pope is not infallible in matters of Scripture unless he is speaking ex cathedra and ---here's where the logical Law of Non-Contradiction comes in--- without abrogating or reversing any or all of the dogma that was there already.
Since 1950, no Pope has claimed to make an infallible statement. Francis has never claimed it.
There are many questions that may arise from the above, and if you want to ask them, go right on ahead.
Bottom line is that some goofball thing coming out of the Pope's mouth is, at best, an opinion (theologoumenon ) and a worst, papal heresy.
That's not an oxymoron, like "giant shrimp."
Thank you for the explanation. Ill freely admit my ignorance on these matters and I appreciate your effort to educate me. Often thats not an easy thing to do.
Best,
L