OpenAI know the exact timelines involved, and what they train on, or do not.

You're right - it is exactly "lawyer speak", rather like Bill Clinton's "I did not have sex with that woman".

Yes they know the timelines, which they've explained. No they don't know exactly what they train on. Even I don't, and my little experiments are nowhere near OpenAI scale. This is par the course for ML. Plus it would kind of defeat the purpose of de-anonimization if they could.