Investors gets ruined on PPAs all the time. With renewables, there's usually some sort of wind turbine or solar park attached, so after declaring bankrupcy the new owners can settle out of court and continue production.

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.