I wish I could pull the reference out of the unreliable stew of everything I have read and heard about jazz that bubbles and festers in my brain, but in truth, it may not have been Dizzy who said that bop came about so black musicians could have a music of their own again that whites couldn't play. It was probably a white critic! I know Diz made the comment about black folks preferring R&B to bop, but I don't think it was from Ken Burns' series. It might have been. It was in a discussion of the financial failure of his big band.
I agree that the Dizzy solo on Hot Mallets is very cool and boppish, almost out of place. It has the same effect that his solos on some of the Cab Calloway records- it sounds so ahead of its time it just jumps out at me.
Another ahead-of-its-time voice on the Hamp Victors was guitarist Oscar Moore on Jack the Bellboy. Hamp with the King Cole Trio all sounded way ahead of anything on record in '40 except maybe some of the Goodman small group sides with Charlie Christian.
Funny that Hawkins opened up so many harmonic possibilities on Body and Soul in '39, then was (I think unfairly ) criticized for some of the records made only 5 or 6 years later like the '44 Keynote sessions or Stuffy on Capitol, for not quite getting bop. There seems to be a kind of barrier that some musicians couldn't or wouldn't pass that resulted in a bunch of very dry-humored recordings just after the '44 recording ban that I would have to call "almost bop".