If your CFD software isn't saving at least the last converged timestep in order to restart the calculation if there's an unplanned interrupt maybe you should implement such a feature! It's been a lifesaver for me many times.
One of the reasons I choose a PC over a Mac is because I want to decide things for myself. Microsoft's updates seem very Appleish to me.
All they need is large text that says something like, "You are more likely to get viruses, malware, randomware, etc if you uncheck this setting." Heck, make them confirm the choice two or three times. Some people want to risk it, some people need to risk it. Let them, it's their machine and their data.
Implementations actually matter. Hordes of us would jump ship if we could, but convincing vendors to port flagship software, or even do something as seemingly straightforward as a license migration is never easy.
Sorry, I have no sympathy. Look for alternatives, or roll your own. Or find a new line of business altogether. Whining about your OS vendor abusing you is getting really, really old now. Like an abusive boyfriend, they're not going to change, so it's up to you to make a change.