OP here. My points were 1) the host said there was a glitch in the airbnb system & doubled booked somehow, but I think they either wanted either a longer tenant or they got a better offer for Marathon Weekend in Boston 2) if I cancel I lose 50% , if they do it they lose 3%.
I didn't initially understand from your post that you would have actually lost 50% had you cancelled yourself even months in advance. I agree that this does seem imbalanced.
That's not the way Airbnb works. You can't cancel someone's booking on Airbnb for a "better offer" from another Airbnb user. If you cancel a guest's booking on Airbnb, Airbnb will block out your calendar for those dates and not allow you to relist your space to rent to another guest - for that time period. If the host HAD double booked on accident through another vacation rental site (Homeaway, VRBO etc), that is the only way they could be canceling to "get a better offer".
One of Airbnb's founders clarified elsewhere in this thread that there actually was a system glitch.
Agreed, my reply was about people canceling to get a "better offer". :) Other than the glitch he mentioned, I think that part of the system actually does work pretty well. Always room to improve though.