They need to answer for that.
That's a commonly-held belief, but runs contrary to the history and law behind the quote. That particular quote was an example in a US Supreme Court case that was decided poorly and later changed (in 1969 I think). In the US, I believe threats of violence or harm are covered by the First Amendment, unless the speech "is directed to inciting or producing imminent lawless action and is likely to incite or produce such action". So the speech has to meet several qualifications to "not be free speech". What those people were doing on Facebook in Brazil would very likely be considered protected speech in the US. Not that what applies in the US applies to Brazil, but since the quote was from a US case, I figured it was with commenting.
Here's a good article about the quote's history: https://www.theatlantic.com/national/archive/2012/11/its-tim...
That's not true. That's way too vague and broad of a claim. In general, specific threats of violence and harm are explicitly not free speech and not protected. And if they're not specific, they're not really "threats". Incitement, fighting words, and other speech often involved in fights where violent threats are made (such as slander and perjury) are all US exceptions to free speech that extend past the imminent lawless action clause.