Your comment might have some effect if there was proof of some authority to dictate any canon, not to mention authority to amend the Tanakh - Canon being an invention of the Roman church...
Neither Christ or the Apostles ever once in any way implied any portion of the Septuagint shouldn't be accepted as the inspired Word of God.
Your mistake is in presupposing the Septuagint was what was used... which is by no means convincing. Further, one would have to prove the acceptance of the anagignoskomena within the jurisdiction of Jerusalem - That being one of the hot spots between the Temple Faithful and the Libertine sect (Greek, Alexandrian Jews).
If that's the "whole bit" you mean you've hit upon the easiest way to identify modern day Pharisees, they obey anti-Christ, anti-Christian, Pharisees and throw out portions of His Holy Word to avoid the Truth contained in those portions of Scripture.
No, the violation of the Pharisees, and their signature, is the promulgation of their oral torah (their tradition) as equal to or in many cases above, Moses' written Torah and associated books composing the Tanakh, including the prophets... In every case, Yeshua stood against their traditions.
The One, Holy Catholic and Apostolic Church Jesus Christ Himself founded
PROVE IT. You can't.
(16) Simon Peter answered and said: "Thou art Christ, the Son of the living God". (17) And Jesus answering, said to him : "Blessed art thou, Simon Bar-Jona : because flesh and blood hath not revealed it to thee, but my Father who is in heaven. (18) And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it.
- Matthew 16 verses 16 thru 18
Christ Himself gave the name Rock (Matt 16:17 above) to Simon Bar-Jona who the Father chose to head His Church until Christ returns. That's clearly stated in the above verses as anyone who is open to the Holy Spirit rather than only to their own Most High and Holy Self can see.
If you can't accept what Jesus Christ Himself clearly said, so be it.