It's never Martin Luther King, Jr, walking up to the stand; it's always the Black Panthers, the Trayvon rioters, Jessie Jackson, hood drug dealers, and hood gang members coming to complain about "The Man" because they need something to complain about.
In fairness I don't think the Panthers belong with the others in this list. When a movement for social change ends with its leaders being killed in a hail of FBI bullets, that's at least a good hint they were doing something positive for the common people.
That's what progressives do: They make real issues illegitimate by associating a group of people with a bunch of whiny babies.
Progressives don't actually want to change the problems they whine about. Rather, they want cushy gubmint-funded non-profiteer jobs "managing" the ill effects thereof.