Anyone who comes on an ex-cultists' forum and evangelizes about any religion is either sick or brainwashed.
However, I am going to agree with the 'echo chamber' comment. People do need to recover from culty beliefs and ways of thinking. Unfortunately, there is no safe place on the planet devoid of such things, so recovery has to happen while avoiding, and sometimes confronting those things.
The forum will address it by modeling appropriate responses.
Freedom of speech is a legal right pertaining to certain (not all) speech occurring on publicly-owned property. It does not apply here.
ETA: I failed to read the post about anti-Semitism prior to posting the above.