i'd say the little bit of skin on the top of a pecker is a bit far off from a limb
it doesn't matter what part it is
it wouldn't be okay to crop their ears, either. or cut off the tip of their nose. anything that involves cutting parts off of your child is not ok
also, judging by your description of it, you don't seem to know what circumcision is, so I'm not sure you're qualified to argue in favor of it