Wow - that should be interesting. I am wondering if he will try to refuse the right to serve them -- don't many restaurants have such a sign/policy. But then if he refuses based on the fact that they're breastfeeding, he could get into trouble.
BTW, I decided to find my state law about breastfeeding to carry it with me in case I am ever confronted about nursing in public.
You can find yours here:
http://www.lalecheleague.org/LawBills.html