It's a common misconception that free speech has no legal limits, and that it affects private companies. Neither of these are true. Hate speech is not protected, and companies certainly aren't obligated to enable it.
Incorrect, it is the US First Amendment that doesn't affect private companies but the First Amendment != freedom of speech. Your statement is a uniquely American misconception.
Freedom of speech, as a philosophy, affects everyone. That's why the ACLU has historically defended some rather deplorable people; liberal principles matter.
It is in fact protected in the United States:
https://en.wikipedia.org/wiki/Hate_speech_in_the_United_Stat...
> ...and companies certainly aren't obligated to enable it.
Nevertheless, it is important to know which private companies do support free speech, including all the ugly bits.