> Social media platforms like Facebook and Twitter are more like a public squares rather than restaurants or stores.
Are they? Let's see the most important difference:
Is a public square privately owned? No. It is owned by the community, usually the council.
Is a restaurant privately owned? Yes. The proprietor has the option to evict people at will, as long as they do not discriminate against minorities in the process.
Do hate speech laws apply in a public place? Yes. If someone states racist things in public, they may be put in prison for hate speech.
Do hate speech laws apply in a private place? It depends on if this space is open to the public, and on the event being held. Generally, yes.
Is the owner allowed to evict any member at will from a public square? It depends. If the person is being harmful towards others, they may be removed from the square and detained, and sometimes even charged a crime.
Is the owner allowed to evict any member at will from a private square? Yes, as long as they do not discriminate against minorities when doing so.
As you can see, the attribute you have brought up does not matter. Facebook has the legal right to remove people for speech, as long as it does not discriminate against minorities in the process.