@Leigh-Anne-and-Jonathan0
As I remember from the summer, some consumer groups had major concerns about guests who were unable to leave a review about a place they found on, or before, or just after arrival that was unsuitable, misrepresented or issues with the host and so on.
I think the British Competition and Markets Authority was at least one of the bodies asking airbnb to change the ability to leave a review as previously it was nigh on impossible to record a review and alert other prospective guests of a full picture of a bad listing. Airbnb changed this from September to allow reviews to be recorded and left for cancellations within 24 hours of the commencement of a booking.
In your case, the guests are allowed to leave a review because of the timeframe involved, but of course it doesn't really meet the spirit of why leaving a review was necessary. It also explains why airbnb are reluctant to remove the review as well, however they should probably really consider it in your case.
In consolation because 'star' marks are very much arbitarily awarded and beyond your control, you should decide for yourself whether you should really give them so much prominence and weight. I am of the belief your future clients will look at your listing description, pore over your photographs and read reviews - and be supremly indifferent to whether you are 5.0 or 4.99 starred or indeed a superhost.