Thank you for writing this post and tracking down everyone’s stated beliefs and updates!
I fear MNM only operated in this case because the prosocial intervention of isolating yourself also happened to be a very selfishly effective intervention. In my view, what this community failed to predict is simply that other people would, with some delay, come to the same conclusions and act as this community did, i.e. going into some degree of isolation to protect themselves. It’s a pretty embarrassing failure! I distinctly recall expecting that aggregate behavior won’t change much until the local epidemic was visibly out of control, filling up hospitals and so on, whereas I of course was going to wisely ride all this out from my apartment.
This would explain why there was no MNM operating in most governments in Jan-Feb. It would also mean we can’t rely on MNM helping out with future risks that have a different structure than pandemics.