On the other hand, I'm glad that I have this information so I know not to install High Sierra on my work iMac (sitting on a desk in a WeWork behind a door whose lock would be very easy to force open) until this is fixed.

[Edit: I now see that there's a simple workaround (change the root password and keep root enabled), so I'm all for "irresponsible disclosure" in this case]

I think this is an unfair characterization. Sure, it's hard to hear that their "hero is irresponsible", but the real reason is that this kind of behavior puts everyone at risk while Apple tries to fix it.