You can sue anyone for any reason. Facebook and other online services enjoy broad immunity from civil suits IF AND ONLY IF they make a good faith effort to remove defamatory content.
I understand why conservative bigots are obsessed with Section 230: its repeal is being used as a threat against platforms that remove bigoted content. Conservative bigots know that Section 230 means nothing to the fact that Facebook can delete their bigoted comments, but they ALSO know that repealing it will cost Facebook money so they are pressuring Facebook, saying "If you allow our bigoted content we will drop efforts to repeal section 230".
I will never understand why people believe conservative bigots who say that it has anything to do with free speech.
Section 230 is literally two sentences, easily understandable by average persons. It has nothing to do with speech.