Your question was: If that isn’t reasonable doubt, what is it?
“Proof beyond a reasonable doubt does not involve proof to an absolute certainty. It is not proof beyond any doubt, nor is it an imaginary or frivolous doubt.”
Your idea that LHO left the rooming house without a jacket is in my opinion imaginary and frivolous. Therefore in my opinion, there is no reasonable doubt.
You can disagree with my opinion. But the Tippit murder witnesses did not use the jacket to identify LHO. They identified LHO and said he was wearing a jacket. Your argument for circular logic is false.
Your idea that LHO left the rooming house without a jacket is in my opinion imaginary and frivolous. Therefore in my opinion, there is no reasonable doubt. It's not my idea that LHO left the rooming house without a jacket, it's yours that he did wear one! You solely rely on an unreliable witness who very likely would have been destroyed on cross examination by a defense lawyer. Reasonable doubt exists when the witness herself says she wasn't paying attention and there is no third party corroboration for what she says.
In this case all you have is Roberts saying that Oswald left the building wearing, what she believed was a jacket (because of the zipper action she could not have seen from the couch), that she had never seen before and that was darker than CE 162.
Marina, however confirmed that Oswald only had two jackets; the grey one and the blue/grey one that was later found at the TSBD. Testimony from Buell Frazier confirms that he saw Oswald wearing a grey jacket to Irving on Thursday night and we know he was wearing the blue/grey jacket to the TSBD on Friday morning. Which begs the question how the grey jacket CE 162 could have been at the rooming house on Friday morning and how Oswald could have left the rooming house wearing a jacket at all, as the blue/gray one was at the TSBD and the grey one in Irving.
That's enough to have reasonable doubt about what Roberts said.
You can disagree with my opinion. But the Tippit murder witnesses did not use the jacket to identify LHO. They identified LHO and said he was wearing a jacket. Your argument for circular logic is false. It seems you don't understand what circular logic is. Your opinion is of no significance and neither is mine. The facts are what matters and in this case you have made my point for me.
Yes, the witnesses did identify LHO in a line up and said he was wearing a jacket, but that only means that the identifications were were probably wrong when it can be established that Oswald did not leave the rooming house wearing a jacket. In order to "prove" that he did, you are indeed using circular logic.