I don't actually get what you're saying here. Are you saying that quoting the Bible, and interpreting Scripture with Scripture, are exotic rules and out of bounds?
How would you use some different, and more legitimate, rules to interpret Matthew 16:18-19?
This gives you a chance to illustrate better rules of hermeneutics. I'm here to learn.
16:13 When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am?
16:14 And they said, Some say that thou art John the Baptist: some, Elias; and others, Jeremias, or one of the prophets.
16:15 He saith unto them, But whom say ye that I am?
16:16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God.
16:17 And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.
16:18 And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.
16:19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
16:20 Then charged he his disciples that they should tell no man that he was Jesus the Christ.
16:21 From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.
Jesus pulls all the disciples aside and asks, "What are people saying about me ... who am I? "
A couple of answers until Peter hits on the correct answer, ":You're God"
Yep, says Jesus, and THAT'S the rock (cornerstone) of your faith. Matter of fact, I'm telling you it will be the basis for the ecclesia to even gather as a body ... one faith ... that I am God"
Now, gather 'round me and let me hip you to some things.
(rough translation from the original Aramaic ... or my imagination ... one or the other)