JayUtah
Penultimate Amazing
I asked if he would agree that Oswald is the only shooter for whom objective evidence is available...
Then again he states that the presence of a second shooter is fact.
This is typical conspiracy rhetoric, reminiscent of the Bellwether Fallacy. Most conspiracy theories cannot stomach the fact that the preponderance of evidence is strongly against them, therefore they have to devise a way for that evidence to be somehow irrelevant.
The boldest way is the bellwether -- some sort of smoking gun that all by itself leads you inevitably, inexorably, and undeniably to the desired conclusion. Then, armed with the "certainty" of that conclusion by that one supposedly direct and irrefutable proof, the theory turns around and circularly dismisses all the counter-evidence on the grounds that it "must" be false since it leads to the "wrong" conclusion. It further asserts that to determine how or why contrary evidence is false is a useless or academic exercise since the conclusion is foregone.
Robert's formulation of the identity of the assassin(s) is a conclusion inferred from the observational evidence he holds to fastest. The central allegation is the direction of the fatal shot. Based on his interpretation of the medical testimony, he asserts the fatal shot came from in front. Therefore, it follows that Oswald cannot have fired the fatal shot because he was in the wrong position, no matter how much evidence places him there and the fatal shot from that direction. But that's an inference, not a fact. It further follows that, the fatal shot having come from in front, the assassin had also to have been in front, no matter what absence of evidence there is for that conclusion. It is not a fact; it is an inference.
A rational approach must distill all the evidence together, understanding that in a real-world situation there may not be a perfectly consistent interpretation of all the available evidence. The parsimonious conclusion is that all the evidence together places the fatal shot from behind and Oswald as the most probable shooter of all those considered. The least painful inconsistency arises in the cherry-picked and mal-interpreted medical testimony, not the position of the fatal shooter.