Given the details of the story, I find it disturbing that this Airbnb user ended up banned for life. To me, that's a severe action which should only be undertaken in egregious or extreme circumstances, and not for trivial violations, particularly if it is arguable that the Airbnb user is not likely to even have known about the policy that they apparently violated.
But as with all Airbnb "bans" of users, they never give a reason, leaving the helpless victims of the guillotine to simply speculate.
For instance, how many of you would have had any idea that posting a review of a host/listing off the Airbnb site, eg on Google (however one does that...I'm not sure) would be a bannable offense. Does AIrbnb have a policy on that? Have they made sufficient effort to educate us all about that, if they do? I do not think so, as I've never heard of such a policy.