Earlier quoted context omitted.
I've enabled root myself and set password on it. After installation of the patch root account was disabled.
Wow. Automatic security update locks me out of my computer without any explicit notice given. How very nice of them.
I'm fairly confident most Mac users never enable the root account at all. We don't need to. I'm not sure people who've only used other Unix systems understand that; I didn't when I came to the Mac after using Linux and FreeBSD in the 1990s. You need an administrator account, but that's not really the same thing. I haven't had a root account enabled on a Mac in about 15 years. (Well, except for a 14 hour or so stretch from yesterday evening to this morning, between the time I enabled it with a strong password as a "fix" for this bug and the time the actual fix was pushed by Apple.)
At any rate, I'd be very surprised if there was even a single user literally locked out of their Mac because of this change. I think it'd have been better on general principle if they'd done some kind of check that boiled down to "if the root user is enabled but it doesn't have a password set, disable it, otherwise leave it enabled," but there may be perfectly valid reasons that they couldn't do that.