If Apple starts being abusive, they'll get their hand slapped. If they don't, they don't.
There's no better company positioned to do anti-malware than the vendor of the OS itself. Which is why Apple and Microsoft both do it. You can disable updates on both platforms if, for some reason, you don't want anything to change on your system without your explicit action (pros and cons to that, obviously). But for most end users, the tradeoff of control vs. security is a very easy one, since the average user is in no way qualified to secure their own system or audit the code that runs on it.