Antivirus software always works as a driver in the kernel, no other way. You'll get the same in Linux, for example. In MacOS it may be slightly better (if I remember right Darwin is a micro-kernel), but in fact a broken driver still can crash the system there.
This page is only about using some APIs, that are now supposed to be called through wrappers. I would say it significantly limits the developers, and also may introduce additional flaws.
