Martin Luther King was not a perfect man. His words and works have been both unfairly heralded and unfairly corrupted. And, I don't know whether he practiced what he preached (or even whether he wrote everything that he preached), but I will say this:
At that time, he was right. Blacks were unfairly persecuted throughout the United States. He fought for change to real injustice and did so in a nonviolent way. And whatever you might say about him, that was a very courageous thing to do.