The way some people toss out the word “corporations” as a bogeyman… they don’t have nearly as much power as is frequently supposed. Unlike governments, for-profit enterprises are highly sensitive to market forces. And when the market says “We don’t like this speech”, they comply. When the market alternatively says “We don’t like suppression of that speech”, then they also comply.
Marketers tend to be very sensitive and generally err on the side of liberalism. Not that I mean “liberal politics” (as the term is frequently misused in the USA as a stand-in for “progressivism”), but liberal as in “more free”. So the speech that is generally unprotected in the corporate world is the type of repressive speech: racist, misogynistic, anti-LGBT, etc. and other forms of speech that are generally considered offensive these days by a majority of folks.
But even so, that speech finds no end of outlets.
Even a major corporation such as General Electric, for example, which boasts over 300,000 employment (world-wide) only represents less than 0.1% of the American population – and that employment number is their world-wide employment, so their American employment is a much lower percentage of the American population. And though the company won’t endorse or even tolerate “under their auspices” speech that they find to be offensive, they can’t control everything that their employees do or say outside of work. And no one can control what people think, or what they say privately.
And “major” employers such as that do not employ the majority of working Americans even in the aggregate. So there’s a lot of leeway, even if major public employers seem to toe the same line.
Don’t forget (though you’re too young to remember, so it’s a thing you’d have to look up to know and then not forget) it wasn’t too long ago in our history that having views that are diametrically opposed to what is considered acceptable today could get you fired. That is, if one expressed support for various “oppressed minorities”: women’s rights, LGBT acceptance, racial equality, etc. – that was anathema.
Pendulums swing. As long as people aren’t overly stupid and overly militant and violent in their causes, there’s room for all of us to speak our piece and get along.