It doesn't say it directly, but it would be a reasonable reading. English, unlike a programming language, relies on pragmatic cues for interpretation. And it's a journalist's job to communicate clearly in their writing.
> Maybe your "they" is ambiguous, does it refer to OpenAI or wealthy entrepreneurs including Musk?
The wealthy entrepreneurs have launched it and, by implication, control it. Thus, OpenAI is opaque solely by the choice of the wealthy entrepreneurs.