So?
It's called telling it like it is.
Few of them know even a modicum of the evidence in the case. The ones that do and still think Oswald wasn't the assassin are just silly people.
So?
There are lots of highly educated people across the political spectrum who are very gullible.
A warped mind isn't necessary to believe nonsense. A lot of very smart people believe some really stupid things. Neil deGrasse Tyson refuses to admit thar men are athletically superior to woman.
Michael Griffith thinks that because 2/3s of people believe in something that means what they believe is true. Or is somehow in some way relevant to what actually happened, to our understanding of what occurred. Do they know anything about the event? It doesn't matter; their view on what took place is somehow relevant regardless of whether they know a single thing about that event. That doesn't make a lick of sense except in conspiracy world.
Even worse, he thinks this non-existent poll of Western opinion seemingly means he gets a blank check for whatever conspiracy fantasy pops into his head. As in: he says Babushka Lady was June Cobb who, he says, was a CIA agent. And that it's "possible" she shot JFK with a gun camera. That's absurd but 2/3s of the people believe there was a conspiracy so, using Griffith's thinking, we need to seriously consider it. After all, you're ignoring what many people think.
Side bar: After ~60 years of this, after all of these investigations, I would have thought that the influence of JFK conspiracy propaganda would have gone away, that reason eventually would emerge. Boy, that was a dumb thought.