There's a line between the OS and third-party software. There's a line between malicious software and accidentally vulnerable. Apple has just shown that it is willing to cross both those lines. Where is the line at which Apple will stop?
To make this look scary, you have to misrepresent what Apple actually did and then extrapolate to some frightening hypothetical to end up at nothing more than a risk inherent in all self-updating software.
If the position is 'all self-updating software is an unreasonable risk', fine. But at least argue that unvarnished, and I imagine to most people, extreme and impractical view instead of trying to dress it up as some novel and intricate argument about morality and creeping authoritarianism.