"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
Internet speech is not the same as freedom of speech. Facebook is a private platform and when you sign-up and use them you abide by their rules. This is not censorship. Facebook can ban whatever they want. They are not censoring anything. They are just denying the use of their platform to spread absurd anti-semitic ideas that have no place in an educated and civilized society.
I have said this before in HN, but I'll say it again. There seems to be this idea that freedom of speech comes with an automatic and superseding right to distribution. That's 100% wrong. You can believe whatever idiotic ideas you want but you can't claim freedom of speech to force other people to give you a platform for your beliefs.