It's important to remember that the National Archives didn't show images. They showed shirts. And I do mean shirts, plural.
This is the shirt they took on a national display tour in 1995. The photo was taken at the display in Houston.
And this shirt below was displayed at the Newseum in Washington DC in 2013 for the 50th.
Obviously, that is a different shirt than the one from 1995. And it is also different from Oswald's shirt which you can see on the right. Look how the margin folded over very neatly like the lapel of a jacket. Do you think the shirt on the left could do that? I guarantee you it could not. Oswald's shirt must have been from Russia from when he lived in Russia. It was made of a softer material and without the hard collar and hard placket that American shirts have. You see, Oswald beat up his killers just by getting dressed that morning. He didn't know he was beating them up, but he was beating them up. That shirt he wore IS his alibi because he and the shirt were in the doorway at 12:30 when Kennedy rode into the Valley of Death.
But, getting back to the National Archives, they have been Ground Zero in the suppression of JFK truth the whole time. Their actions prove that they know that Oswald's shirt exonerates him. In fact, it's interesting to consider what happened to Oswald's actual shirt. I wouldn't be surprised if they destroyed it, just as they did the original Altgens photo.