[abdullahkhalids]

If you think of it as a You vs Landlord negotiation, indeed, the landlord is permitted to do whatever he wants such as not renting to you because he has a better offer elsewhere.

If you think of it as Society vs Landlord, there are many reasons that Society can give to justify preventing the Landlord from Airbnbing. Such as, society has a duty to provide housing to locals, airbnb guests make residential areas more dangerous, dirtier and noisier, other standard reasons why businesses are not permitted in residential areas.

If these reasons trump the positive impact on the region from encouraging tourism, then, regulating airbnb makes sense.