In other words, the bishops credentials to teach and lead depend on their moral worthiness? No one is morally perfect.  All have sinned.  All have fallen short of the glory of God.  If you think a morally perfect life is the only thing that qualifies a person to teach and lead, then there is no one on earth qualified to teach or lead and no one you will follow.  

A person can always come up with excuses for why they disobey someone in a leadership position.