Hello @M54,
This isn't Airbnb support. It's a forum where Airbnb members like yourself help each other with advice from their own experience. Members here don't have any input to what Airbnb allows or doesn't allow.
If a reservation isn't cancelled Airbnb makes the assumption that the guest checked in and stayed.
When this isn't the case the host should contact Airbnb to tell them so and ask that the review be removed.
For ways to contact Airbnb support ...
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.