For instance, Catholics can and do debate whether the statement has fulfilled the criteria --- ALL of the criteria --- set forth in Pater Aeternus. That's why there are debates, e.g. about whether canonizations, or the statement on the priesthood being essentially a masculine vocation, or the statement that every marital act must be open to the transmission of life, are infallible.
A statement can be authoritative without being infallible in the formal sense.
So he is only infallibly passing on God’s message to him, after the others decide if they agree with it or not.
That doesn’t make it sound like it is infallible. Even in assigning Sainthood to people, the denomination doesn’t agree if God really told him to, or if it was just his personal decision to do so.
It sounds like the infallibility claim of the Popes, is not very accepted by their church members.