You missed the context:
these guys were being bad and they got an appropriate bitch slap. Hopefully that's the end of it. I'm sure none of them are genuinely bad guys.In other words, the point of them being "genuinely bad guys" or not is whether the affair should be allowed to blow over after a few firm but loving reproaches. staunch and cookiecaper are both speaking in the same terms, on the assumption that only "bad guys" need to be punished harshly, because non-"bad guys" want to behave well and just need a mild wake-up call now and then.
Rejecting the concept of individual people with persistent qualities forces you to argue in different terms, but it doesn't necessarily change the result of the argument. So let's talk about punishment from the opposite orientation:
People exist in complex fields defined by their personal relationships and social institutions. People tend to engage in behavior that results in comfort, advancement, and social approval, they and tend to avoid behavior that results in deprivation, loss of position, and loss of social capital. Harmful behavior is controlled by ensuring that personal relationships and social institutions punish bad behavior instead of rewarding it.
In this case, that means society should find out what these people did, enforce any laws against it, and (in the case of people who know them and work with them) shame them with disapproval and show an aversion to dealing with them. Otherwise bad behavior will flourish and affect more people. We do not want to be responsible for tempting people to behave in ways that are injurious to others, because aggressive, selfish behavior harms those who engage in it as well as their victims. If we, as a society, do not inflict just punishment on those who harm others, then aggressive, selfish behavior will increase, and there will be more suffering for both victims and aggressors.
tl;dr: Rejecting the idea of "genuinely bad guys" leads to the conclusion that they should be punished regardless of whatever personal characteristics might be ascribed to them.