Another Stadia user here. While I agree that Google should be responsible for compensating customers for their losses if they shut down the service...it wouldn't hurt Larian to offer a free Steam copy (or heavily discounted) to those that lost the game, if Stadia were to shut down.
I mean, we've already purchased the product. It would cost virtually nothing to allow us to have it in a different form. Forcing us to buy it on another platform would be doubling their money due to our misfortune. I don't think any company wants to be seen like that.