>he specifically notes that they used the paid subscriptions, iirc.

Where are you seeing that? He only says "We used several LLMs throughout: Anthropic’s Claude, OpenAI’s Codex, especially with GPT-5.6 Sol and, more recently, Astra. The latter was only used for writeups and auditing our arguments."

I might be missing something, but he doesn't seem to confirm that he opted out, at least in the written writeup, maybe he has on social media? He also likely had early access to Astra given the timing, and I thought early access customers couldn't opt out? (Am I wrong about that?)

The paid subscriptions have opt-out for sharing data for training purposes. I think it's on by default.

Paying for an account doesn't opt you out by itself, right? Has he stated anywhere that he actually opted out? But if not, then I also don't understand why OpenAI's communications about this have been so vague, they could've just said that he didn't opt out, using those chats in training data follows their ToS and that's it (whether that's "fair" is a separate discussion).