There are some areas where it's problematic - such as companies curtailing political speech or, particularly, union speech. But businesses should try to make a safe workplace for its employees and customers, and part of that is not having to put up with hateful speech. And businesses have the right to set standards in those areas.

Bryant

We live in capitalist hell, though, so...

are usually defending their right to be assholes.

Which is one reason free speech exists, so that assholes feel free to expose themselves for what they are. 'Free speech' ensures their visibility to the general public.

Your comments are pretty much spot on, though. Like many things, it boils down to common sense in most cases.

to conflate being able to say whatever you want anywhere with political rights to dissent.

Being reasonable and aware includes the context one is speaking in in relation to the subject chosen and one's personal viewpoints. In corporately controlled environments there are strict structures that curtail and even punish speaking too freely, as in any tyranny.

However, it is important to retain our perspective on free speech where I think it was intended to be sacrosanct, and that is the freedom to speak out against injustice and to express political dissent, especially when it is informed and cogent communication.

Otherwise, the expectation of being able to spew insensitive or ignorant remarks in social settings is merely a lack of awareness, consideration and eloquence. Claims to "free speech" in such contexts is merely applying civil and legal rights as an excuse to be rude, inept or egotistical and belies common sense.

Many employment contracts involve clauses that do not allow for causing harm to the employer's reputation. Thus it is by no means true that one can always 'say whatever you want' in public communications as a private person. Private communications are one thing, but blogs, books, tweets that are racist or otherwise harmful to the employer's image are not 'say anything' zones for many workers.
So your theory that one can be the HR VP of a company while writing a racist blog on the side without being fired is full of crap. The concern is not just for YOUR public image it is for the public image of the company. Celebrity is a special case but also relative in that within industries some people are very well known and thus they are just that.

however those terminations have been contested (of course, as employers have a distinctly limited right to curtail peoples' actions in their personal lives) and I'm not aware of the outcome of those appeals.

Please do feel free to provide real-world examples of the kind of situations you are referring to, including the outcome of legal challenges to such terminations. I am all for more complex and complete understanding.

coming here spewing their contaminated bile day after day.

We already know that we have less than zero to learn from them, so constructive boundaries have been devised to limit their ability to post here.

Example:

I can't see the pic, but that's a perfect example.

I always enjoy seeing trolls crying about their inability to grasp this concept in their screeds in the hate mailbag.

Safe bet, that.