The author of this editorial piece doesn’t know what they’re talking about. The author can’t seem to make up its mind as to whether MLK embraced this ideology after the speech or whether or not the “movement” embraced it after MLK’s assassination. This author just seems to be trying to make a case against affirmative action through the use of MLK’s words. If you look at the state of the country when that speech was made, you’d see how foolish this person is.
Regardless of the retired professor’s political views, his history is poor. This page (from a collection of MLK’s sound bites) indicates a philosophical difference with Stokely Carmichael’s Black Power. It is dated 1967. If this quote was made in January (and it might have been made in December), it would have given Dr. King only 15 months to change his mind and “embrace” Black Power.
While that is possible, it is certainly not my memory of events at that time, which included criticism of Dr. King for not embracing Black Power.
As to the opinions on the linked site, that is a matter for Great Debates, not GQ.
MLK embraced the tactics of civil disobedience a la Ghandi (passive resistance). Calling upon the masses to disobey unjust laws is indeed a way of voicing power, black or otherwise, however the term Black Power was primarily associated with the groups who advocated a “by any means necessary” approach, whether violent or not (active resistance).