"Ruby", the one we see in the televised spectacle, was wearing a jacket. Everyone knows that. Everyone can see that. Nobody doubts it. He was presumably struggling against Dallas Police, but he was DEFINITELY wearing a jacket at the time. Then, they dragged him into the jail office and immediately pushed him down to the ground and handcuffed him. There are several accounts of this, and nobody said that they first removed his jacket. It was Detective McMillan's handcuffs that were used, and it makes you wonder why he didn't take them out and use them in the garage. But regardless, the story is that Ruby got cuffed immediately inside the jail office, and he was definitely wearing a jacket at the time he was cuffed.
So, how could he be photographed handcuffed with just a shirt on and no jacket soon after the scuffle? They would have had to remove his cuffs; then remove his jacket, and then reapply the cuffs. Do you think they did that? There wasn't even time.