In the US, the First Amendment he's so busy pushing is specifically a protection against impingements of freedom of speech from Congress (and, by extension, anything else that represents the US Government or State Governments). And even in that case, it's not an absolute right, because, for example (see City of Chicago v. Alexander, 2014), "The First Amendment does not guarantee the right to communicate one's views at all times and places or in any manner that may be desired."
It's also clear that just because you have a right to insult somebody, doesn't mean you have a duty to. Calling officials of a school "Benito Mussolini", and shouting at them, may or may not be a protected Amendment right, but it's basic decency to find a better way to put your point across.
Or, put another way, if the best you can say about your argument is that it isn't literally illegal, then you need a better argument.