Server side doesn't violate user's system with rootkits. How to detect things with good level of correctness using server side AI is a good question. But it's a much better problem to solve than how to add even more privacy invasive malware on the user's system.

> How can you tell if someone is running an aimbot or just has good aim?

That's the point. I don't care. As long as the game is enjoyable. And I'm sure AI can be gradually trained to detect cheating in more sophisticated manner do differentiate non human from human patterns. Not a trivial issue, but something they should invest money in as above, instead of rootkits.