With all due respect, MLK, Jr. was one of literally hundreds of leaders of the civil rights movement during his time, and one of thousands during the 100 years following the Civil War. In fact, someone else would have stepped up as they already had–MLK, Jr. just had more press.
Again, no one is diminishing his accomplishments, but frankly, to allocate a national holiday to him is fine–to have people say it’s racist or ignorant for private companies to operate on this day is absurd on its face.