Defining dark horse: "a candidate or competitor about whom little is known but who unexpectedly wins or succeeds."
Compared to Altman, Emad Mostaque is a relative nobody and a somewhat controversial figure at the head of what is apparently one of the frontrunners of the AI industry. Additionally, releasing the model, something that was I assume very capital intensive to create, is definitely a bold business strategy, and not one we've seen succeed yet despite the popularity of Stability's models and its derivatives within the open source ai community.