It wasn't a mistake.
Grasp that and you might quit being such a repetitive bore.
I'm not quite sure whom you are referring to. But your comment is rude and shows a fundamental misunderstanding of the situation. In the old, pre-internet world people could say "I've made a decision, I have the power, no-one can challenge me". In the internet age every decision can be challenged.
It is indeed possible that the moderators' decision to ban this member was not a mistake. I don't have the information to make a determination on this (though on the basis of the information in the public domain it was surely a mistake). But it is certainly a mistake for then to assert that their decision is beyond challenge. The mods might be able to point to rules and regs which set out that their decision cannot be challenged - well fine, then these rules and regs need to be challenged. The old age is over; now we have a new method of working. The old power structures are in the process of being demolished by the power of the communication of the internet. Here at LPSG we are seeing a little corner of this global movement. It may be that LPSG will align itself with the future and with systems of accountability and fairness. Or it may set itself against them. If the latter in the short term there is nothing we the members can do about it - absolutely nothing. But it would demonstrate a mindset that will inevitably be swept away in the tide of open-ness created by the internet, and would be so very sad.
A reasonable analogy would be with homophobia. The mods are demonstrating the communication equivalent of homophobia - they appear by their actions to be phobic about communication and open-ness and accountability. On the basis of the information they have presented to members their decision to expel a member is beyond justification - it is like saying it is right to beat up someone because they are gay. Just as homophobia is now recognised as being unacceptable so this phobia about communication and open-ness and accountability should be recognised as completely unacceptable. I have considered that maybe there is some good reason to exclude the member in question. Is he for example under 18? If so, tell the membership. Otherwise accept that the moderators who usually do a good job might just possibly in this one instance have gummed up, and in doing so have created a pretty nasty environment on board. I know of two regular posters who have stopped posting - there are surely others. The mods have the power to enforce their edict. But do they really want to act in this manner?