Microsoft are more than just Office, Outlook etc... This isn't 1994.
They will not tell the UK to 'suck it' because places like hospitals, universities and other major companies including essential ones rely on such vital services. It would be astonishingly hypocritical if they even remotely took this line because MS are still trying to worm and maintain their way in certain Russian domains. Money isn't everything and the knock-on effect that removing such services would be absolutely catastrophic globally. Imagine seeing Cancer Research UK have their entire portfolio left in limbo or be lost because some American company had a hissy fit about not being able to buy another multi-billion dollar company ran by a pervert that employed perverts.
The CMA's findings were perfectly legitimate and Microsoft have already delayed their final submission to the EU commission because it will not be even close to passing just like several other Amercian companies in recent years and these have to be respected. It's already embarrassing enough that Bill Gates's bum boy Brad has thrown his toys out of the pram in spectacularly ignorant fashion but now arrogant corporations are finding it much harder to buy their influence and presence all over the world and it's glorious to see. The US Federal Trade Commission has already opened legal proceedings against the deal citing competition laws so for them to blame the UK solely when that lawsuit is not concluded, nor has the EU assessment been completed is just beyond stupid. They have much tougher hills to climb with the FTC and EU so if they can't convince the UK then the current deal will be dead in the water and they only have themselves to blame.