They're doing nothing illegal, I'll still speak out what I observe to be sad unfolding of events.
Another angle here is that social media companies are ultimately just plain old telecom companies. We regularly regulate private businesses and limit the ways in which they conduct business. Your electrical utility is not allowed to deny you service based on your political opinion. These companies shouldn't be able to do so either, as they are common carriers (https://reason.com/volokh/2021/07/16/conclusion-social-media...).
Additionally, social media is built on network effects (https://en.wikipedia.org/wiki/Network_effect). The larger the network, the stronger the service, but also the higher the barriers to entry. Businesses built on network effects inherently face limited competition and must be regulated since they do not face competition as much.
Finally, our government is already censoring speech by hiding their influence through these social media companies. Tech companies have an incentive to play nicely with the government, since they might otherwise face difficulties like anti-trust action. Glenn Greenwald had written extensively about this proxy censorship:
https://greenwald.substack.com/p/how-silicon-valley-in-a-sho...
https://greenwald.substack.com/p/congress-in-a-five-hour-hea...
https://greenwald.substack.com/p/democrats-and-media-do-not-...
The problem is their betrayal of the spirit of the internet. We built the internet with a vision of optimism, but now that the vision is in danger. When things become difficult for only a moment, we abandon that spirit altogether. For shame. It'd be much better if their service didn't abandon it. The Internet has been the great social experiment of our time. I'll take any opportunity to speak out against actions that diminish free and open discourse.