Sure, but your argument is for "shouldn't act". It's not the same as argument for "avoid getting involved". They can't choose not be involved, there's literal

Sure, but your argument is for "shouldn't act". It's not the same as argument for "avoid getting involved". They can't choose not be involved, there's literally no way to avoid being involved once you're providing facilities. The act of producing software which "does not moderate user generated content" is an action demonstrating a particular set of values. It's not neutral.