The Yahrzeit is a sacred remembrance of a Jewish person's family and ancestors. Please keep this discussion about the proper observance of a Yahrzeit rather than a discussion about MLK YS"Z.
http://www.wzo.org.il/en/resources/view.asp?id=893
What do you expect from liberal secular Jews?
They turned Rabin into a Tzaddik Gamur, why are you surprised they did the same to MLK?