Earlier quoted context omitted.
Harassment can be punished by the law. So that is the "now what". No, freedom of speech doesn't mean that you can engage in serious harassment of people, their workplace, or their children or family.
The scenario being discussed is employers looking at employees’ public statements, or third parties telling employers about those public statements. I don’t think that’s anything close to harassment.
The question was about "to get a social media frenzy going".
And this is never just an employer randomly looking at a tweet, for which they are almost never going to do anything about it. Most employers don't care.
Instead, the much more likely scenario is mass points of harassment, stalking, and death threats targeted at people's friends and family, when such a "social media frenzy" happens.
You cannot ignore the actual mostly likely result of your advocacy. And when you just say that this is all "free speech" you are doing disservice to the massive amount of illegal harassment that these internet mobs cause.
You do not control the mob, yet you are response for its harm anyway if you try to start one.