So, yes, I do believe that these people would probably deserve a bit of the support that some programmer at google receives after being fired for being slightly stupid.
I wouldn't even doubt that almost everyone would declare their support if asked (Presidents excepted). It just seems as if nobody particularly cares enough about it, emotionally, to go out of their way to show their disapproval in the same way they do on other issues.
Considering the accusations against the police, such support would also help to actually determine what, if anything, went wrong, and could possibly prevent a repetition, or escalation.
If everyone just shrugs their shoulders and says "yeah, I guess that's bad. Obviously", there's no pressure to do anything that could potentially harm the careers of those involved.
To be honest, though, I don't see complaining about it here changing that. I think it's better to focus your own attention at problems that require it, in your opinion.
For example, if you feel the people were wronged and HN crowd should hear about, why don't you submit the article?
I don't understand your contention here. You seem to complain that people do not spend more time discussing obvious thing (mob justice offline) rather than non-obvious thing (mob justice online). I think the reason for that is obvious. Or maybe you just want a "collective outrage" instead of discussion?