An admin shouldn't be banning people for actions in a thread they got personally invested in. Delegate that decision to another member of the team if you really think there are serious problems. (It helps if you don't also kick someone off your team at the same time ...)
And if you're going to ban or remove privileges from people then you need to explain at least to those people what they did wrong, otherwise you just look like you're on a power trip. Particularly if bans are rare and you suddenly hand out a whole bunch in one go, breaking precedent for the site.