I think that Quincy Jones's opinion on the Beatles is not especially relevant to his "disclosure" about JFK.
The interview goes on to cover music, and Jones, an extremely high level composer and arranger, shows an elitist view that the majority of music is beneath him, and who generally holds Jazz musicians in much higher regard than Pop ones.
As for his thoughts on JFK, they are either true in full, true in part (i.e.e The Mob did it but acted wit the CIA).
Or he has been told something that is not true -
- perhaps in error, or because someone, somewhere, wants him to say this information in order for it to be disinformation.
I have no idea at all which of the above it is.
I only ever met one person who had met JFK, who met him one average once a month, had dined with him the week before he was killed, and only had good things to say about him.