By that logic, the NT should never ever be used as Scripture, because:
1. The NT books post-date Proverbs 30.5-6 by a long way
2. Scripture never lists any 27 NT books as Scripture; and never hints at the existence of any Scriptures other than the Jewish ones, and possibly 1 Enoch.
And Jesus of Nazareth never said a word about them.
So by normal Fundamentalist logic, none of the NT books can be Scripture. They are too late, they are not recognised as Scripture by the Jews, & they contradict the Jewish Scriptures. Basically, they are Bible fan fics, like the Book of Mormon. By normal Fundamentalist logic, that is. By that logic, they are, at most, purely human productions, and are to be used as such.
Maybe Fundamentalists should repent of their unScriptural exaltation of those 27 books as Holy Scripture. If Jesus had no need of them - who are Fundamentalists, to call them Scripture, when He did not ? If Fundamentalists were consistent, they would realise that the Jewish Scriptures were all “done away in Christ”, and that True Christians™️ are led, not by dead and and carnal “Holy Scriptures”, but by the Spirit of God, because the Law of God is engraved upon their hearts.
For non-Protestants, these facts are not problems, because we do not attempt to construct Christianity out of the Bible. Nor do we divorce Sacred Tradition from Sacred Scripture.