IMO, it sounds like an excuse to get out of the booking.
I know you guys welcome people with open arms, to what (by all accounts) are lovely, comfortable, reasonably priced, homes. Ultimately though, this is your (and Tamara's) business, and it's just rude.
If there was a reason, they should've put on their big boy pants and had the courtesy to explain. Wouldn't change anything, but at least you wouldn't be scratching your head.
Next time, remember most of the people on PiA are randoms; being a member is no guarantee they are a decent human being.