Whether a thing is legal or not doesn't mean everything that stays within the legal bounds is desirable as a society or morally, ethically just. Many of the most atrocious deeds of humanity have been legal at the time they were carried out.
By saying all of this I am not doing myself a service here. Such opinions get downvoted on an US dominated platform like this one. I still think it is important to note that any freedom we are gurantueed comes with a duty to protect these freedoms for others. Those who enjoy a freedom and at the same time try to take that very freedom away from others can not complain if a free society tries to defend itself and limits their rights.
When thinking about how societies can stop aliding into fascism after the genocides of the second world war Austrian philosopher Karl Popper coined the term "paradoxon of intolerance" for this. Any free society that wants to survive, cannot be universally tolerant — otherwise the intolerant will abuse that "hospitality" and abolish that free society. That means any free society has to be intolerant towards the intolerant, after a certain degree. I would argue this degree has been reached in the US a while ago.
Protected speech is a strong word in a nation which killed civilians on foreigns soil based on what they have been communicating via SMS without a trial. Here, suddenly, it is okay to go after people based on what they say somehow?
How is the impediment happening? If through the threat of violent or illegal action, then that should be illegal. If it's libel (false statement, made while knowing and believing that it is false, with intent to harm), then maybe it should be illegal too. Otherwise, it's protected speech.