I think people seriously underestimate how hard it is to get the GPU compute/etc that is necessary to be useful here. Lead time would be years, easily, even if you had the money. NVidia can't change this for you even if they liked you - they literally can't build chips fast enough.
Depending on the exact agreement, Microsoft may have just given them credits/free use, and the part where they make sure the resources are actually available is just good faith that may no longer exist.
That's one example.
Even beyond that, you are assuming they can only do super-direct things, but it turns out to be fairly easy to make things very uncomfortable for people/companies indirectly.
Huge portions of the compute they are using is also directly doing inference for Microsoft products, so that's another dimension to all of this.
You also have to remember that ultimately Microsoft had to sign an operating agreement that states that the primary duty of the for-profit is the mission and charter of the non-profit and that all other things are secondary to that.
Not that any of that makes Satya happy, but it does severely limit his options outside of cutting off his nose to spite his face. I think the primary outcome is in significantly reducing the chances Microsoft continues to invest.
I'm just giving an example of where they do have leverage if they want to use it despite the cost.