It's not ridiculous @Tony1190 , when you booked you signed up to Airbnb's long term cancellation policy which has a minimum cancellation period of 30 days.
If you knew that your work circumstances were likely to change you would have been better making a shorter term booking with a flexible cancellation policy (less than 28 days) and then extending it, if you needed to.
Unfortunately it seems your host isn't too familiar with how Airbnb works if they think you not getting a refund for the first 30 days under the long term policy is ridiculous.
If that is what your host says though, there is an easy solution, they can just chose to voluntarily refund you more of a refund than you are entitled to under the cancellation policy you booked under.