microsoft has to operate under some form of law, and most countries have computer fraud laws (especially in the US, where it's a federal law). Writing a program to exploit someone else's machine for your own financial gain is certainly computer fraud, so they would be prosecuted for it.

How would this be different from say, a pirated copy of MS Office/Adobe PS that detects it has been pirated and stops working?

Pirates have no rights whereas paying customers do.

It's also bad publicity for them. I suspect many companies will look into Linux/Mac in certain cases.