You're playing with words, using a sort of ordinary-language-philosophical re-invention of the idea of free speech, and saying, why doesn't it apply to the blackballing someone from a job. In paragraph 1, you suggest that it's legitimate protest. In paragraph 2, I'm actually relabeling it (not sure what that means, but yes - it's a real world example).
Your paragraph 1, though, has the thoughtful query of exploring what is and isn't freedom of speech, and throwing out some scenarios to mull over. I agree that This principle you have of consequence free speech can only exist as a principle. Once it interacts with the complexities of the real world it becomes impossible to actually define, legislate, and enforce fairly.. How about, the spirit of the principle of freedom of speech could be that we don't strike fear in people who express opposing views.
Should it be illegal to make a personal decision not to buy a company's product? Reductio ad absurdum fail. No, because aside from being stupidly unenforceable, it has nothing to do with shutting down opposing views. Company listening to protesters and firing a company? Should it be illegal? It should be illegal on the basis of workers' rights, but I don't consider it freedom of speech to fire anyone or to keep them. It's another category of problem. Basically: it sounds like you're trying to defend shutting down speech by looking for ways to say that it's freedom of speech to do so.
Since you are fishing for 'first principles' (as a tech-centric board I can see how sexy it is to try to re-invent the concepts and throw them out as unworkable, as if law were mathematical), how about we think about the abstract 'spirit of the law' so-to-speak, and break out of the idea that since the idea of freedom of speech is imperfect, it should be thrown out. Because if you consider SUPPRESSING speech to be an 'expression' of speech, then it sounds like you're attacking the entire foundation of it, and we just don't align on values. We're in the realm of the social, the legal, cultural, not in the realm of absolute principles or foundational mathematical notions. I am not suggesting that, again, it should be ILLEGAL or LEGAL to do very specific things (we can spend forever mulling through scenarios), I'm suggesting - a few messages up in the thread - that if we don't CARE about freedom of expression, things like blackballing people from a job or deporting someone on a green card are perfectly OK. And I 'both sides-istically' purposely showed examples of the Right doing it, and the Left doing it, in order to provoke people to go back to thinking about the abstract principle of it.
The LEGAL matter is a different category, and super interesting to talk about. It's philosophy, it's Supreme Court precedent in the U.S., there are some fascinating speeches by ACLU figures like Ira Glasser, their arguments in the old 1st Amendment cases of the 20th century.