I think this is actually pretty conclusive. There were a number of people near the knoll (which makes it a really bad choice for a shooter, in multiple ways). No one near the knoll spotted a shooter or reported the effects of shots right next to them.
Yes, it certainly
is conclusive. So much so that if the conspiracists were to ever correctly acknowledge even a fraction of the known facts and evidence of the assassination, their game would be over. Even
they would have to agree that Oswald did it, alone, not just beyond a
reasonable doubt but beyond practically
any doubt.
So the conspiracists stay in business only by blatantly and repeatedly mischaracterizing the evidence: i.e., lying. They correctly assume that most people won't bother to check them on it. The few who do are simply ignored until they eventually give up from the utter frustration of trying to talk to a brick wall. The conspiracists then claim victory by default.
It's a battle of attrition based on a kind of magical thinking: anything you say, no matter how self-contradictory, illogical, bizarre or just plain false, can become true fact if you merely repeat enough to outlast those who contradict you.
One of profmunkin's many examples is his feigned disbelief that Norman, Williams and Jarmin could not detect Oswald's shots from directly over their heads. Not only did they most
certainly detect Oswald's three very loud rifle shots, Norman also heard Oswald operate the bolt three times, each time ejecting a shell that Norman heard hit the floor. All three quickly and correctly concluded that the shots were fired from almost directly above them. Not only do we have their consistent testimony on this point, but we have pictures of them taken from ground level showing them right where they said they were. And the Warren Commission verified by direct experiment that Norman could easily have heard the sounds he said he heard.