>> Is it legal to discriminate against someone in a job based on what is on Facebook?
Is it legal to discriminate in hiring based on a candidate’s persona? Sure it is. Show me the law that says you HAVE to hire jerks, profane individuals, promiscuous individuals, party-boys and party-girls who will be hungover every morning, weirdos with strange cult beliefs, etc.
What a candidate posts on facebook, tweets, etc. is part of that persona.
Note that the OP isn’t about someone being “discriminated against” for their posts once they were hired (that may well be unlawful). It’s about vetting them DURING the hiring process. It’s hugely important these days to vet any and every way you can, because once you hire them you are sort of stuck with them.
How well we know