"he is stuck between a rock and a hardplace.
frying pan or fire? which should he choose?"
He's chosen to tell this woman that she is not welcome in his restaurant, via a friend!
So he has chosen the path of least resistance.
Any restaurateur with class would have welcomed her with open arms, suggested she bring any other friends with similar disabilities, and offered special lunchtime menus - that sort of thing.
Advertise locally that disabled people are welcome - and that they are delighted to have the renowned artist amongst their regular clientele.
A professional restauranteur would tell customers where to stick their ignorance and lack of empathy if they complained - whilst having in place an effective set of procedures for people that refuse to pay.
His business is clearly struggling, as he says he lies awake at night worrying.
One woman could not decimate a healthy and well-run business.
As it turns out, this man has clearly picked on a well-connected and extremely determined lady.
Good for her for making as much noise in the media as she can.
It is possible, of course, that she is an annoying, loud, flamboyant, artistic creature that has been a bit of a pain ever since she started frequenting his restaurant, and he is now using her disability as an excuse to ban her.
Either way, he has cooked his own goose(sic).
His lack of professionalism and awareness will be his downfall.