Well, Buell is a friend and I know him very well. That being said, friends can lie. Friends can "conveniently" forget. I don't think he's a liar nor has he forgotten anything. He had no reason to lie about anything at all. He was 19. He was threatened with a Decker Hold. He stood up for himself and he told the truth. He has never believed Oswald took a shot.
Buell Frasier suffers a similar guilt complex as Marina Oswald.
Marina refused Lee Oswald's plea (the evening of 21 November 1963) for her and the children to live with him in an apartment near Dallas. Marina intended to agree eventually, but was making Lee suffer a little for the argument (by telephone) they had earlier in the week. She knows that an agreement to reconcile with Lee might have prevented the assassination of President Kennedy.
Buell unknowingly drove the alleged assassin of President Kennedy to work on 22 November 1963. Although Frasier claims the package Oswald carried into the TSBD was too short to contain the Carcano rifle disassembled: This can be seen to be an opinion developed to avoid accepting that he inadvertently and innocently assisted the assassin of JFK. Hence ... Buell Frazier declares that he "believes" that Oswald "never took a shot". He bases that opinion on his perception of Lee Harvey Oswald's personality which he has stated as "nice".