I believe what the post meant to communicate is:

- alpha testers will start getting access now

- everyone will get access Thursday (barring banned countries / individuals)

Historically, some companies and individuals have gotten alpha access before public launches, to give feedback and adapt their products to the new models. With GPT-5.6, some folks had early alpha access, but this was paused while the model was being evaluated and approved. Now, alpha access will be enabled for partners in the next two days before our wider launch.

(I work at OpenAI.)