I seriously doubt this is fake, the airbnb-mm.com domain is owned by Airbnb Inc and they have every right to stop the improper usage of their registered trademark. A domain name is a different animal than just using their name in an article, which is fair use and free speech -- assuming you leave the mark in place or attribute it properly.

IANAL but the author of that article you linked is wrong from what I understand. A domain name has been enforced in the past as a violation of the mark and is not the same as free speech. It is of course up to the company to enforce it and take action. They may choose not to based on circumstances but they will send out the form letter at minimum to show they worked to enforce it.

Technically it isn't from AirBNB, but, it is from Mark Monitor who is authorized to protect AirBNB from infringing domains.