You picked up exactly what I was throwing down. Morality isn't just a moving target, it's basically omnipresent at all times. Native Americans found honor in robbing or killing strangers. Some cultures have arranged marriages, some involving children. How should it be judged? Do we condemn everyone who lived prior to the great awokening for not ever having so many humanities grads with so little to do?
Dr. King preached the importance of faith and that no man shall get to the Father but through Jesus. The alternative is to spend infinity in unimaginable torment. Quite a bit longer than a few decades in torment. If Dr. King drove one person to lose faith through his transgressions, how would Dr. King judge that? How would he weigh it up against a guy who pleaded with his state leadership against secession prior to the war, then promoted reconciliation after the war? As I said, some people who share Dr. King's beliefs could interpret his actions as worse.