> If you configure Firefox to not automatically update, and then use, say, a package manager to update it, automatic updates will get re-enabled.
That isn't what the bug report says - package managers don't use the Firefox installer. Are you talking about a real bug (if so, is it logged?), or are you spreading FUD?
Depends on the package manager. On Windows both Ninite and Chocolatey use the Firefox installer and re-enable Firefox's automatic updates.
If you configure Firefox to not automatically update, and then use, say, a package manager to update it, automatic updates will get re-enabled.