Lech Lecha 5873.
appx. The Minchat Chinuch ends up rejecting the Nodah Biyehudah's son's answer with the following difficulty: if really בני נח don't use the principle of רוב in their halacha, then wouldn't every בן נח have to be circumcised, because they come from a population with a מיעוט of בני קטורה? Why does the Rambam limit his ruling to ישמעלים specifically?