Section 230 says that ISPs are not treated as the publisher or speaker of what their users publish or say. That does not mean that prosecutors cannot try to find companies criminally responsible for allowing users to post illegal content on their platforms, especially if they have knowledge of such content. See Backpage. And even if the companies win, the battle itself is quite damaging.
Furthermore, Section 230 says nothing about how the court of public opinion will treat the provider. These companies are thinking about more than just the legal repercussions. If their business suffers because people do not want to do work with companies that support this kind of content, then all the Section 230 protections in the world will not bring in revenue.