Are the ones being ban also workers of this person?

(I use the word person as "gentleman" is surely not what this guy is)

I don't think anything legal can be done unless he has them as workers and more than just a ban is going on, maybe he is telling them they can not work certain jobs and so on b/c of their faith. This is a tough call to make and I'm not really sure, but if its just a member of his forum and nothing more, its possible he could get away with it.