Getting someone fired for saying shit you find deeply offensive is not a betrayal of the principle of Freedom of Speech.
Something that everyone needs to keep in mind is the first amendment is a legal concept in place to stop THE GOVERNMENT from restricting speech, meaning they can't put you in jail for speech. Regular citizens, on the other hand, also have the right of free association, meaning they can remove people from their property for any reason, including speech. A company has every right to fire someone for bringing them bad PR. Otherwise youd go into a store and the cashier could tell every customer to eat shit and they wouldn't be able to fire them, which is not a world anyone wants.
So what does Freedom of Speech mean to you as a principle? Should I be allowed to post scat porn on this sub? Should an employee of a store be allowed to tell people they hate them enough that people stop going to that store?
Of course not, it's an ideal to strive for, not a concrete thing that can actually be achieved. People should be able to speak openly without retaliation, the retaliation being reserved instead for their actions. However this only works when you have a population of sufficient moral quality, which we no longer have. Thus it is a conundrum.
I'm an idealist at heart, but I'm not stupid enough to ignore the ugly reality and the required curtailment that lays before us. I simply weep for the loss of something good that could have been maintained but wasn't.