@Kellie66 No, there is not a "Contact Guest" feature for many reasons - privacy for one, and also prevention of guests being solicited and spammed. If the previous guest coincidentally happens to also be a host with an active listing, you could visit their listing and use the "Contact Host" feature.
If the host is pursuing a claim for damages, and you dispute the claim, Airbnb will likely ask him for evidence of the damage. But if he's not seeking funds and you only object to the public review, the best thing to do is write a public response to his comments. Future hosts can cross-reference his listing and decide which they believe more.
There was a complaint from the guest that came to one of John's properties right after you, about finding a large amount of dog poop left behind in the yard, so a sleuthing host would likely believe that the host was correct about the damage.