[Dantilla]

Reading his review makes it obvious he is not a normal person.
If I was looking up your business, I'd laugh at the idiot and ignore the negativity.

A couple years ago a business renting space from me asked if I would buy it, as the owners were approaching 80 years old (still full of energy. Fantastic people).
In my due diligence, searched reviews, and only one was negative, but obviously written by a scatter-brained, over emotional whiner. Long-winded whining, with no specifics of how the business wronged them.
I mentioned this to the owner, and got a big eye roll. "I know who that was, there was no satisfying her."

Maybe respond with: "We are glad this "customer" will not return, as we both felt threatened."