That's not at all how Section 230 works. There's a popular myth that it distinguishes between "publishers" (who make editorial decisions about what content is shown and how it is shown) and "platforms" that just host it with minimal interference, but that is in fact just a myth.

However, I don't really see how Section 230 is even relevant here. What Section 230 protects them from is for being liable for what is in the individual user posts posted to Facebook. It essentially just makes it so that if you have a beef with what someone posts on Facebook and want to sue you sue the poster rather than Facebook.

What is being alleged is that Facebook's decisions in how to arrange and present and show or not show that user content has harmed people. Those are things that are not in scope for 230.