There are only three groups of people who could be subject to betrayal here: employees, investors, and customers. Clearly they did not betray employees or investors, since they largely sided with Sam. As for customers, that's harder to gauge -- did people sign up for ChatGPT with the explicit expectation that the research would be "open"?
The founding charter said one thing, but the majority of the company and investors went in a different direction. That's not a betrayal, but a pivot.
To an extent the promise of the non- profit was that they would be safe, expert custodians of AI development driven not primarily by the profit motive, but also by safety and societal considerations. Has this larger group been ‘betrayed’? Perhaps
Just because they sided with Altman doesn't necessarily mean they are aligned. There could be a lack of information on the employee/investor side.
GP didn't speak of betraying people; he spoke of betraying their own statements. That just means doing what you said you wouldn't; it doesn't mean anyone was stabbed in the back.