This looks like the final cell-phonification of the Mac. I'm bummed.
But they're right - if you assume that a significant fraction of Mac users are going to install some sort of third-party interface with an LLM, it is either significantly extend and harden the security perimeter deeper into the OS or your customers will routinely have everything exfiled as a matter of course, and it would just be cheaper to make iCloud into an anonymous FTP site.
And given Zuckerbook's demonstrated willingness to brazenly, actively subvert OSes, I'm willing to bet they're going to go Russian on their subjects, er, customers, anyway. ("You probe with bayonets: if you find mush, you push.")
It will probably be what finally pushes me to a Linux laptop, though. I'm old, I spend a lot of time at the shell. I like Macs because they're great unix workstations, still. But I don't see how you can accommodate both people like me and people who need to be protected not only from themselves, but from Zuckerbook and worse.
And they're a much bigger market than people like me. And "AI is the Footure."