Frazier is...certainly not an expert on the evidence against Oswald.
I think you're right. He's not an expert. And it could be that Buell has deliberately avoided becoming well-schooled on the evidence so that he can continue to maintain a (false) rosy picture of his friend and co-worker Lee Oswald for as long as he lives.
But I really have no idea as to how much Buell knows about the details of the JFK case. As I asked in my article in the OP, I'm wondering if Frazier even believes Oswald shot and killed J.D. Tippit. I have a feeling he doesn't believe Lee took a shot at anyone in 1963 --- including Walker. But for that matter, is Buell even
aware of the Walker shooting at all? You'd never know by looking at any of his interviews. That topic never comes up. Nor does the topic of Tippit's murder. It's as if those things never even happened....which is one of the reasons I wanted to write out the above list of questions for Buell Frazier. If he were ever to study those questions, perhaps he would be inclined to accept the fact that Lee Harvey wasn't always the perfect co-worker after all.