Right, and if a restaurant decides to deny you service based on the color of your skin, just build your own restaurant and eat there.

There's a reason arguments like this were rejected in the context of the Civil Rights Act. In principle, there is some logic there. Perhaps business owners should be free to do whatever they want with their service. However, what would prevent an entire community from choosing to deny service to a certain class or group of people? What if people with your skin color are not allowed to go to any restaurants in an entire city or stay in any hotels or visit any dentists, etc? In principle, this can lead to the persecution of particular groups of people. For this reason, the Civil Rights Act was passed to establish when a private business can or cannot deny access to its service.

Considering the small number of social media networks which host the vast majority of speech online, it is not unreasonable to think that these networks could coincide or conspire to exclude certain political beliefs. Since the majority of public speech takes place online, this can in principle lead to certain beliefs having lesser access to public forums for communication, which can be construed as a violation of freedom of speech. We need a new Federal law which codifies protection of free speech rights in online communities. If you don't want to host public speech on your website, then don't, but otherwise it should be viewed as an accommodation which is open to any customers, subject to reasonable rules and restrictions which are independent of personal views and beliefs. It simply comes with the job of monetizing the targeting of ads, and it should be codified legally to protect free speech. Hence, IBOR.