I see it as just a way to make anyone's understanding of Scripture purely existential. When you reduce it to that, one is no more "correct" than another. In fact, it must assume there is no correct way. Knowing where you are probably trying to drive this point to is in accepting that there MUST be only one "infallible" interpreter and it is the one you have insisted is the only divinely entitled one - your Magesterium. I think you have overplayed your hand.
Of course! (more refined than 'duh!'; doncha think!)
Just looky here:
27 So he started out, and on his way he met an Ethiopian eunuch, an important official in charge of all the treasury of the Kandake (which means “queen of the Ethiopians”). This man had gone to Jerusalem to worship, 28 and on his way home was sitting in his chariot reading the Book of Isaiah the prophet. 29 The Spirit told Philip, “Go to that chariot and stay near it.”
30 Then Philip ran up to the chariot and heard the man reading Isaiah the prophet. “Do you understand what you are reading?” Philip asked.
31 “How can I,” he said, “unless someone explains it to me?” So he invited Philip to come up and sit with him.
32 This is the passage of Scripture the eunuch was reading:
“He was led like a sheep to the slaughter,
and as a lamb before its shearer is silent,
so he did not open his mouth.
33 In his humiliation he was deprived of justice.
Who can speak of his descendants?
For his life was taken from the earth.”
34 The eunuch asked Philip, “Tell me, please, who is the prophet talking about, himself or someone else?” 35 Then Philip began with that very passage of Scripture and told him the good news about Jesus.
36 As they traveled along the road, they came to some water and the eunuch said, “Look, here is water. What can stand in the way of my being baptized?” [37] [c] 38 And he gave orders to stop the chariot. Then both Philip and the eunuch went down into the water and Philip baptized him. 39 When they came up out of the water, the Spirit of the Lord suddenly took Philip away, and the eunuch did not see him again, but went on his way rejoicing.
(Some manuscripts include here Philip said, “If you believe with all your heart, you may.” The eunuch answered, “I believe that Jesus Christ is the Son of God.”)
And again, the problem with an infallible interpreter is that even if he makes an infallible pronouncement, everyone who hears it is just as likely to fallibly interpret it as they are likely to fallibly interpret infallible Scripture.
So adding more layers of infallibility doesn’t help any unless the hearer has the ability to infallibly interpret as well.
If the hearer can infallibly interpret, then he can infallibly interpret Scripture and doesn’t need someone to infallibly interpret for him.