Microsoft was blindsided by OpenAI's ouster of CEO Sam Altman - https://news.ycombinator.com/item?id=38312372
But on other other side of a hypothetical situation spectrum, it could also mean something like "Our agreement with OpenAI provides us with robust fallback access to Source Code, Training recipes and Model data in escrow should a particular trigger situation happen."
Ultimately, that amounts to the same thing you said anyway.
Microsoft lost more than $20b on Nokia, Skype, WinPhone and RT OS, and barely blinked.
But given the usual verbiage / pomp-and-circumstance (etc. etc.) on typical announcements, getting something so short and simple like this just feels weird.