If you disable update via policy (which is the only way you can do it now that about:config method is removed), then going to "About Firefox" doesnt give you any options regarding updating.
I did check them. I set my settings to "Check for updates but let you choose to install them." via the about:config method, which is the setting I assumed they were referring to.
I could still update from 72.0.0 to 72.0.1 from the About Firefox menu item, and from the about:preferences#general page. I'm running Mac OSX Catalina.
That said, Firefox is definitely doing what they can to make users keep auto updates on. I do think there should be a way to manually update if you've disabled both auto-updates and their update checks, without requiring the user running the installer, forcing you to toggle one of those settings off again.
If you disable update via policy (which is the only way you can do it now that about:config method is removed), then going to "About Firefox" doesnt give you any options regarding updating.
Check your facts.