A critique of OpenAI from an insider who worked there can only come from an insider who worked there. Nobody’s going to swear a vow of poverty and then work at one of these places.
You don't need to be an insider to make any of the author's assertions. An insider is useful if they're a whistleblower, when they're saying what everyone else is seeing and saying (and they hired a PR firm to do it) it's something else.