Probably because: “Prima Sedes a nemine judicatur.”
“Prima Sedes a nemine judicatur.”
I thought this was interesting:
https://novusordowatch.org/2016/03/impossibility-judging-deposing-true-pope/
There is a difference between judging the pope and judging whether a given individual *is* the pope.
If I’m not mistaken, the pope has to be Catholic. If Francis claimed to be a Catholic and for whatever reason is not, is he the pope? Was he ever the pope?