This is intrinsically important to this conversation. I would submit that covenants are delivered by a single individual, and are not subject to change or amendment thereafter by secondary agents. The disciples who came after Moses did not have authority to change Moses. They had authority to handle things within Moses, but did not have any authority to add to or take away from... To include Yeshua, regardless of His stature. It is the signature of YHWH that what He said will not change, and will not return to Him empty. This includes all agents - judges, prophets, etc. in order that the original words are not clouded and made null.
The very same thing has to apply to Yeshua's message as well, if for no other reason than continuity's sake - The disciple cannot change what the Teacher taught, or the teacher is made to be wrong... A precept that the super-secret decoder-ring crowd rarely take into account. For the purpose of interpretation then, the words written in red must needfully carry primary authority. While the words of Paul or Peter or John are truly inspired, their words must needfully be passed through the filter of their Master's words, because like the Torah, the Master's words are forever.
Diminishing those on the other side of the discourse does not usually result in edifying them, it doesn't matter how right you are otherwise.
I agree and what you posted is exactly how we see the flow of scriptures from Genesis to Revelation. God is Holy, we are not. God desires men and women be reconciled with Him and He provided the Way. That has been the flow of everything since the Fall of man.