If it is shown that Oswalt didn't kill him then there's no reason for tourists to pay to enter the Texas Book Depository Museum. So they have to keep the story they're selling or risk losing revenue.
And look at all the books, movies, TV documentaries they get to make. It's been a million dollar industry to talk about what happened.
I never really had an interest in the case until circumstance drew me in. On my honeymoon, we went to Washington DC on a whim. We visited the Capitol, the Washington Monument (which looks down on the baseball field where the "Day The Earth Stood Still" landed their flying saucer}, and ultimately we went to see Arlington Cemetery on the advice of some we met.
There I saw the Kennedy gravesite all covered in a marble memorial engraved with his many quotes. After that, I found myself paying attention to these many documentaries that pretended to present evidence for your consideration as if you might figure it out.
Fast forward about 20 years and I end up in Dallas/Fort Worth for training for work and I convince my travel partner and driver to go to Dealy Plaza.
I don't know what I expected. The documentaries analyzed Dealy Plaza from every conceivable angle. And like I said, you think that's some way of solving the mystery. But when you stand there, you get nothing. Just an empty and sad feeling that people were able to murder the President in front of the whole county and get away with it.
But it completed my tour of President Kennedy from grave to crime site.
Then I recently watched the interview with the guy who claims to have been a shooter from the grassy knoll. As he talked about that day in Dallas, you realize that it's no mystery at all what happened. The Zapruder film showed us all what happened.
By the time the lengthy interview with the shooter was over, you had the creepiest feeling because the story was told by a cold blooded killer who saw what he did as just a job to be done. It's scary to hear how freely a group of killers and others moved about Dallas in the time leading up to the killing.