I'm pretty sure OpenAI did know about this.
The wiki publicly logs all visitors, and we see a lot of traffic from OpenAI offices right before the agents stop editing the site.
I'm in favor of much more transparency so that we can prevent future incidents with much more capable AIs and existential stakes.
i really hope openai didn't know about this, might be the worst decision in the history of this field if they deliberately chose not to disclose it. the impact on trust would be very hard to recover from