Hindsight? King lived in a time (as did my parents who grew up in Miss.) when there was NO justice for a black person. To them, injustice was just too real. King's generation took the best chances they could get to seek any sort of balance.
Marshall was radical. But remember, that generation SAW things that would absolutely unacceptable today (ie. James Byrd's murder) and often nothing was done at the time.
So, maybe, just maybe, you are looking at King's generation through pc blinders.
Look how many times Byron De La Beckwith had to be tried in order to convict him of a crime everybody knew he committed. De La Beckwith (I still can't figure out what the deal is with that name) was the O.J. of the sixties!