The suggestion that there is any real possibility that Oswald may not have snuck into the TT is weak sauce. Obviously he entered the theatre because he was there when arrested. Postal - the only ticket seller - didn't sell him a ticket. Burroughs - the only ticket taker- didn't see him or take his ticket. Oswald had no ticket in his possession. Postal sees the "man" coming from one direction, she looks toward the street where the police activity is occurring and then is approached by Brewer who asks if the man bought a ticket. Postal looks down the street in the direction the man was heading and doesn't see him. Brewer identifies the man he was following was Oswald. So where does Oswald go if not into the theatre as he passed behind Postal? He is not anywhere to be seen on the street. But we can't conclude from this that Oswald snuck into the TT? Silly.
These contrarians are laughable in trying to establish an impossible standard of proof for any fact they don't like and then suggest there is doubt about an obvious fact. Oswald clearly "snuck" into the theatre. We don't need a time machine to confirm that. By that nutty standard, no one saw Booth shoot Lincoln. They heard a gunshot, looked in the direction of the sound and saw Booth holding a smoking pistol at Lincoln's head. How are we to know that he shot him? There must be doubt as to the matter. HA HA HA. Maybe Lincoln committed suicide and Booth just picked up the gun? Just endless contrarian nonsense.