Not a valid comparison?
If you look at circumcision and vaccination as procedures that are left to the discretion of the parent, I would say MA's comparison is valid. There are people who still refuse to have their children vaccinated.
I think your argument was two-part. One being circumcision inflicts suffering on the child and the other that the procedure has no medical benefits. Have you ever seen a line of kids waiting for shots?
I do agree with you that circumcision should be an elective right of passage, left preferably to the adolescent.