Did you listen to the way Roy Vaughan said it? Because, if you haven't listened to the way he said it, you need to listen to it.
He says it with conviction, like he knows it to the core of his being that Jack Ruby did not come down that ramp.
"I'll go to my grave saying Jack Ruby did not come down that ramp."
Roy Vaughan indeed went to his grave saying Jack Ruby didn't come down that ramp, and he was right, not wrong. He just left out an implied part of the statement: "on my watch." Jack Ruby did not come down that ramp on Roy Vaughan's watch.
But, there is no reason to doubt Jack Ruby that he went down the ramp because he's just as believable as Roy Vaughan.
Jack Ruby: "I noticed a police squad car at the head of the ramp and an officer leaning over talking to him with his back to me."
That would mean that the officer leaning into the car was on the west side of the ramp, which was Ruby's side, not the east side (the Pearl Street side) which was the side Vaughan went to get out of the car's way.
And that means it was a different officer and a different time. Look at this map:
So, Ruby walked east on Main Street, crossing Harwood, to get to the ramp. He said the squad car was at the head of the ramp, and an officer on foot was leaning into the car with his back to him. It means the officer must have been leaning into the driver's side of the car, which is the only way his back could have been to Ruby. But, Roy Vaughan said many times and every time that he got out of the way by moving to the Pearl Street side. Today, it's the Pearl Expressway, but then it was just Pearl Street. Vaughan said nothing about leaning into the car to talk to Pierce. He said that his response to the car coming up the ramp was to step towards the street, but not into the street, to check for traffic and then to wave it on. There was no delay. There was no chit-chat. The car didn't stop at the head of the ramp as Ruby described. It just kept going. It must have been a different time that the car stopped at the head of the ramp with an officer on the other side, the Harwood Street side, from which Ruby was coming, where the officer was leaning in talking to Pierce and with his back to Ruby.
So, we are talking about two entirely different situations. Pierce must have made two exits; one earlier when Ruby was there, and one just a minute before the shooting when Ruby was not there. Vaughan was there for the second exit but not the first. Vaughan did not begin his watch until after the first exit had happened.
What's the alternative? That Vaughan lied or was negligent and mistaken? Bull Shit! There are no grounds to go there, and the good Friar Occum will go for your throat if you try. That Ruby lied? Why would he lie about that if he was willing to accept that he shot Oswald? You think he lied to protect somebody who helped him get in another way? Why would he do that? Where is there the slightest evidence that Jack Ruby lied about anything? He was a man pleading to take lie detector tests or even swallow truth serum. Ruby didn't lie about anything.
The solution to this is that Ruby got there early. He walked down the ramp, got jumped and swifted up to the 5th floor. And then they proceeded with the televised spectacle using James Bookhout as his surrogate. Bingo. That is what happened.