I think it was a real mistake to create OpenAI as a public charity and I would be hesitant to step into that mess. Imagine the fun when it tips into a private foundation status.
Was it a mistake to create OpenAI as a public charity?
Or was it a mistake to operate OpenAI as if it were a startup?
The problem isn't really either one—it's the inherent conflict between the two. IMO, the only reason to see creating it as a 501(c)(3) being a mistake is if you think cutting-edge machine learning is inherently going to be targeted by people looking to make a quick buck off of it.
Only the current setup is feasible if they want to get the kind of investment required. This can work if the board is pragmatic and has no conflict of interest, so preferably someone with no stake in anything AI either biz or academic.