Second: is this about freedom of speech? If it is, say so, because moderation nor censorship exclusively define that. Muddying the debate by giving some weird definition of two concepts isn't going to help that.
Freedom of speech is a right that concerns you, a citizen, and public authorities. Censorship, in return, is when that right is interfered with by [the public authority] blocking your speech.
Moderation is when a [private entity] is blocking your speech. There is no public right that is interfered with in that case. You have the right to say what you want without public authorities interfering, but you don't have the right to say what you want in my house.
(Note: this definition is different from the one used in the article)
Whether or not Twitter is infrastructure, and therefore moderation equals censorship would be different debate.