I hesitate to point out that if the legislation prohibits crimes in the Church, you argument would preclude non-criminals from legislating unless they were guilty of the crime which is the subject of the legislation.

Perhaps psychotics should only be treated by inmates of the institution, dental caries by those with rotted teeth, and an infarction by a surgeon suffering a heart attack.

It's really an untenable illogical position, but I do appreciate that it gets repeated quite a bit to attack the Catholic hierarchy in lieu of an actual argument.