It's sophistry because under your definition it is impossible for Facebook to apply any form of control over the content on their platform, which they are clear

It's sophistry because under your definition it is impossible for Facebook to apply any form of control over the content on their platform, which they are clearly entitled to do. Your definition (accepting for a moment the opening paragraph from the Wikipedia article on censorship as a "definition") can be logically reduced to, "Suppression of information which may be objectionable by a group". That, for instance, describes HN comment and article moderation. It is so overly broad as to be able to describe practically anything.