It's pretty clear what he means by free speech here. In the grey area between legal and illegal are the topics we consider taboo. Many platforms simply censor these subjects, OP wants to understand why.
The simplest answer is that content moderation is an unsolved problem and certain topics are expensive to moderate. Freedom of speech matters but so does the culture of conduct. Further, as a site owner you risk your reputation by the activity you permit, and taboo subjects can attract folks you don't want on your site. Hence why they end up in the cesspool.
The simplest answer is that content moderation is an unsolved problem and certain topics are expensive to moderate. Freedom of speech matters but so does the culture of conduct. Further, as a site owner you risk your reputation by the activity you permit, and taboo subjects can attract folks you don't want on your site. Hence why they end up in the cesspool.