Breastfeeding is perfectly natural and beautiful. There are ways to be discreet about it and I think the mother should do what she can to not make others uncomfortable. But a bathroom, no way-too dirty.
I breastfed three children and there are times when you just can't find an isolated place. I am pretty shy, but I learned how to get as far away as I could and use a blanket. There is always the chance, though, that the baby will pop up for a look around and there may be a slight exposure, but you have your blanket. Why would anyone object to that?
Do they want the mother to have to stay home all the time?