@Olivier5,
I don't think that this line of reasoning applies to slavery. For one thing, slavery can easily be undone.
But not surprisingly, the moral arguments supporting male genital mutilation can also be used to support female genital mutilation. Again, my point is that these arguments vary greatly from culture to culture.
You changed "genital mutilation" to "clitoris excision". I don't think is valid... there are many types of genital mutilation that don't involve excision. I don't think that removal of the male foreskin is at all equivalent to removal of the clitoris (in terms of medical seriousness or loss of sexual function).
However, I think in modern Western cultures... any modification of the female genitalia is met with horror, while male circumcision is still acceptable.
This cultural difference is interesting.