The MLK of mainstream knowledge gave a pretty speech in Washington D.C. for the history textbooks and then went home.
The authentic MLK called upon each and every citizen to examine themselves and do difficult work to correct grave injustices that pervade society — not only in terms of race/civil rights, but also in terms of warfare, and the economy. Note accurately that his transformational work wasn’t even close to finished when it was cut short by an assassin’s bullet in 1968, was actually rolled back in many ways in the decades that followed, and remains undone today.
So, the opponents of the authentic MLK bring up his infidelity and all sorts of other failings that are routinely excused by those same people in white politicians, especially white politicians named Donald Trump.
MLK was a uniquely talented communicator but his ideas are in no way unique to him. They were part of a broader political movement of the 1960s, and they’re carried forward today by Bernie Sanders most prominently, and were championed for a long time by the late Rep. John Lewis, among many other Democrats and Black Lives Matter/progressive activists.