You've erected a strawman. The argument was not "free speech doesn't apply to companies", it was the exact opposite, i.e. a company's prerogative to control speech on their platform comes downstream of their own free speech rights. This remains true today and the article does not argue otherwise.

No, the argument is definitely "you have no expectation of free speech if you're using e.g. facebook to deliver that speech". Which is certainly an opinion to have, but in my view a silly one. You might as well say that if you chose to send mail using a "private company", it's that's company's "free speech right" to inspect your mail and throw it away if they don't agree with the contents.