I don't mean to be cynical, but I read this move as: OpenAI scared, no way to make money with similar product, so acqui-hire the creator to keep him busy.
I'd love to be wrong, but the blog post sounds like all the standard promises were made, and that's usually how these things go.
It isn't an acqui-hire just a simple hiring. Also unless creator is some mythical 100x developer, there will be enough developers