This is not difficult. The mother is right. The father is a fool. And that's the trouble with democracies -- fools are alloted equal time to have their views heard. And those, who by experience or education, know better, have to listen to them.
I realize kids shouldn't always get their way, but if the boy has suffered infection and discomfort I think he should be heard and allowed to have relief. I've never heard any information that would cause me to think it's harmful to have a circumcision. I would think he'd rather be comfortable than [imagine alternative.]