They're accepting your definition of censorship to highlight how fucking stupid it is. Is Hacker News a censorship haven because I flagged the "How to have Sex with Cars" post uploaded yesterday? Am I a tyrant for trying to oppress that poor user's voice? No. I'm upholding the guidelines of a privately owned and moderated community.

"Censorship is censorship is censorship" is the sort of defense you'd rely on if you were caught selling guns and kiddie porn on the internet. It's not the sort of defense OpenAI needs to use though, because they have a semblance of self-preservation instinct and would rather not let ChatGPT say something capable of pissing off the IMF or ADL. Call that "censorship" all you want - it's like canvassing for your right to yell 'fire!' in a movie theater.