They have the right to do that in their own home (or maybe in your country, in public), but in a private space owned by a company, they have to abide by Terms or Conditions of Service. Swastikas, genitals etc. are prohibited. End of story.
I'm also a little tired of people rolling out the notion that free speech is a "right". It's about time people started realising it's a privilege. One not enjoyed by a great many inhabitants of this planet. It should be cherished as such, not abused by ignorance.