What anti-semitism? Jamnia is a council of Jewish rabbis that rejected Christianity and established a Jewish canon. Thus its determinations are irrelevant to Christians -- not because of ethnicities but because of religion. The nationalities of the people at the foundation of Christianity are not relevant either ("no Jew nor Greek", St. Paul says). So where do you see "antisemiitsm"?
It was the comment "What Jews accept for their own canon is irrelevant" that I was referring to, not the specifics of the finding of the council at Jamnia. The Jewish Canon had been established long before Jamnia. There was clearly an accepted Canon before Jamnia for Old Testament books. Jesus refers to "Thus saith the Scriptures" The Bereans searched the Scriptures. They were not searching miscellenous old writings. They were searching Scripture. Jewish Scripture. And what they, the Jews, including Jesus, Peter, Paul, et al., considered Scripture is HIGHLY RELEVANT to what we consider Scripture today in the context of Old Testament (and New Testament if we are discussing the Messianic Jews mentioned). There were the prophets and the law. There were the books of poetry. Many of them were referred to by Christ and were quoted in the New Testament. The Jews did not consider the Apocryphal books Scripture at that time. Jesus never disuaded them of that opinion. Thus, what Jesus considered to be Scripture is quite relevant and the fact that he was a perfect Jew at the same time makes it even more important.
Now, as to the antisemitism, I have just seen it run throughout the thread, mainly with the RCs. I do not agree with the scholars at Jamnia in so far as they rejected Christ and Christianity. However, to discount what the Jews considered Scripture at the time of Christ because of what the Jamnian scholars did with the New Testament is a mistake.
The Canon was settled before Jamnia for the Old Testament. It did not include the books known as the Apocrypha.