I still can't believe more people complain about this being publicly disclosed than this being possible in the first place. No one is obligated to know the procedures on InfoSec 0-days and follow those steps.
My guess is he found this vulnerability on accident, freaked out, and tweeted about it. Probably has limited infosec experience.
So he's either not reading his replies or he's being deliberately irresponsible. My guess, based on his profile and online behavior, is that he's trying to ride the coattails of getting some exposure online.
I think the problem is due to the fact that they are fans. In this case, it's Apple, but there's no reason it couldn't be Linux or Go or whatever. Regardless, any bad news about their hero is irresponsible to disseminate. We see this same phenomenon in politics, in sports and elsewhere — I daresay it's regrettable human nature.
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.
I'm pretty sure any fix has to go through Build and Integration before being rolled out. Then you need to have people actually install the update…
If you read through the comments, you'll see people are arguing that Apple is to blame here. It doesn't require much discourse to recognize that's the case and hence why you don't see more people complaining about this being possible in the first place.