When the "reasonably intelligent" LHO was confronted by police seconds after the shooting and found to be calmly sipping a coke on the second floor he would have recognised, as "most criminals" would, what a godsend that was, the next best thing to a solid alibi. "Most criminals" would instantly realise the way to play it is to hang around and tell everyone he'd been seen on the second floor seconds after the shooting by his boss and the police. Instead he chooses to slip out without telling anyone knowing it would make him the prime suspect. If LHO was the sole assassin he deliberately spurned his golden opportunity of an 'alibi' and chose to incriminate himself. He also chose to incriminate himself by carrying in his wallet false ID that linked him to the murder weapon, something "most criminals" and "reasonably intelligent" would definitely not do. Think about that. He knew he'd have to leave the weapon behind so he carried false ID on him linking him to the weapon.
Lastly, if LHO was the lone sniper he would've took the shot with the limo coming towards him down Houston Street. Put yourself in his position, a clear head shot as the target moves slowly towards you or a shot through the trees as he moves away? If you are "reasonably intelligent" the answer is unavoidable.
Oswald knew he was already a person of interest to the FBI even prior to the assassination. He knew his rifle would be discovered on the 6th floor and likely traced to him. For all he knew there were perhaps witnesses and other evidence that would soon link him to assassination. He wasn't going to hang around the TSBD and tell everyone he had a "golden alibi." That's maybe what an innocent person would have done but Oswald had no such luxury. Instead he had only one option. To make like Michael Jackson and beat it while he could. Using his flight to suggest innocence instead of guilt is quite a bizarre argument.
The false ID argument is again basically that the evidence is so strong that we can only conclude that Oswald is innocent! LOL. Criminals often do stupid things that get them arrested. Oswald either forgot that he ordered the rifle under an alias, didn't think it could be traced back to him because he had no idea what records Klein's retained from the transaction or just didn't care because he knew getting arrested or killed was part of the equation in deciding to assassinate the president. His goose was cooked the moment he pulled the trigger. What was he going to do? Assassinate JFK on Friday and just go back to his regular life the next week because he got rid of the fake ID? Maybe he thought a fake ID would be useful on the lamb. Regardless, citing the presence of highly incriminating evidence that links Oswald to the crime as the potential basis to exonerate him is a head scratcher.