@Alon1 I'd expect that involving media, Twitter, etc on this would backfire pretty badly. The complaints would basically draw more attention to how easy it is to get an EC cancellation. And it's hard to make the case that Airbnb's decision was damaging to the host, in the context of the booking being half a year away.
@Inna22 I don't doubt at all that the guest lied and forged a document to get out of the booking (though it's the first time I've ever heard of the "evidence" being sent to the host and not just to Airbnb). But I also assume that Airbnb operators are required to accept any documents they receive as if they were valid for a few reasons:
1. Their staff is not qualified to validate documents from 192 countries, in dozens of languages
2. In many countries the host cancellation policies are superceded by consumer protection laws that guests can invoke to prevent being forced to pay for goods or services not rendered.
3. Per the terms of service, the host has essentially granted Airbnb the final say in all matters concerning payments in transactions that go through its platform
Which is all to say, you are right in principle but it's not a winning battle.
I do, however, think Airbnb should overhaul its entire approach to cancellations. Too many variations that have no real purpose because there are so many loopholes, exceptions, and grace periods. I'd prefer it if guests could simply opt into a cancellation-protection insurance scheme, and making a claim through the insurance rather than having Airbnb reach into the host's pockets for refunds.