Presumably, if it's just a per-agreement to purchase power, there's no downside in the likely case the project implodes.
FWIW I agree with the author of that Data Center Dynamics post, it's quite likely that MSFT and Helion are essentially in cahoots by stoking investors with vaporware. But it also seems like Altman might have sold Nadella 50MW of magic beans.
[1] https://www.datacenterdynamics.com/en/opinions/microsoft-and... This is second-hand, the agreement is not public.
Here there's realistically no way to continue electricity production so the assets will likely be chopped up and sold, if possible. Nobody owns anyone anything and Microsoft doesn't have to pay a dime. They won't get their power of course, but there's no downside for them.
These types articles where a PPA contract is confused with an investment is really common, mostly for nuclear and renewables, but that doesn't make them any more true. Microsoft hasn't invested anything, likely because they know this is (pardon the pun) hot air.