Why is MLK censored

I was just chatting with my friend with league messenger, and I figured that MLK is censored. I was just trying to tell him that I have a day off tmr cuz it's MLK day, but instead I have to type Martin Luther King Day since it's censored. I don't see how MLK is a swearword or whatever. Anyway, just letting yall know if youre also wondering why it's censored. May peace be with all of us.