Postal saw Oswald whether you like it or not...
"Johnny asked me if I sold that man a ticket. I asked him what man. He said that man that just ducked in here. I told him no, I didn't, but I had noticed him as he ducked in here." -- Julia Postal
Postal then called the police...
"The officer asked me if the man fit the description of the suspect. I told him I didn't know because I hadn't heard the description of the suspect. I told the officer that I would describe the man to him and that he could take it from there." -- Julia Postal
Mr. BALL. The last time you had seen him before he ducked in, he was just standing outside of the door, was he?
Mrs. POSTAL. No, sir; he was still just in----just off of the sidewalk, and he headed for the theatre.
Your problem, Bill - well, actually his and the others doing this - is that you are trying to reconstruct what happened, to solve a murder. Sure, you have biases like we all do. Confirmation bias, motivated reasoning. All of that fancy sounding stuff. But you are looking at the totality of evidence and trying as best as you can, again given our human failings, to explain what happened.
He's trying to exonerate Oswald. He's not interested in trying to figure out what happened. He's trying to clear his guy. So, Oswald is totally innocent, all of his actions can be dismissed or ignored while everyone else's actions are given sinister explanations. Why Oswald? Heck if I know.