Martin Luther King jr was in my opinion very close to a saint. However his image today and his reality back then differ.
This is only human. Politics is about interests. What can be good to one group of people is maybe not good for the other group. in politics good and bad is most definetly a matter of on which side you are on.
People like Mahatma Ghandi, martin Luther King and nelson mandela are all had a common goal; to deliver a people from oppression. This is what i would call a single goal (not diminishing the enormous efforts necessary to reach that goal, or the sacrifices it took). Politics is about serving multiple goals all at the same time. It is not black or white but gray. MLK never 'ruled' in the political sense (holding public office) and therefore we can never determine how he would have ruled. We know how he served his people in life and in his untimely death.
To be humane in politics is ,in my opinion, almost impossible. Being humane might look to be the best course but perhaps in the later run it only damages the people who elected or put their fate in that person.
Being humane to one can mean being inhumane to the other.