Libel law explicitly applies only to factual claims that are false and damaging to another person's reputation. Opinions, including the ones Elon Musk expressed

Libel law explicitly applies only to factual claims that are false and damaging to another person's reputation. Opinions, including the ones Elon Musk expressed, would very clearly be protected speech in the context of libel law. Why these restrictions on libel law? Well, because of the First Amendment. Again, why should the courts restrict libel law to such a degree but allow labor law to dictate what opinions someone can or cannot express? (We can all accept, I hope, that Musk's tweet was his opinion.) Also, which constitutional rights are in conflict here? Labor law is just enacted law, not constitutional in nature. If labor law conflicts with the Constitution, the Constitution wins.