They don't. LN kooks assume a priori that no doubt pertaining to their faith-based belief system is "reasonable".
LN kooks try to argue that things that are not evidence of anything (like "going home mid-week") somehow constitute evidence, because of their lack of actual evidence.
LN kooks think that silly presumptive rhetoric (like "frenzied flight" and "Oswald's rifle") somehow makes a weak, conjecture-based argument stronger.
Wow so much hysterical anger, calm down for a moment, John, and let's examine why the rifle is actually in fact Oswald's rifle.
Oswald ordered the rifle.

Oswald paid for the rifle.

Oswald received the rifle.

The HSCA expert confirmed the rifle Oswald was holding in the backyard of his rented home on Neely street was indeed the same rifle.

Oswald touched the rifle and the FBI confirmed that Lt. Days print came from C2766.

C2766 was discovered on the 6th floor of Oswald's work place.

Oswald's prints were on the rifle carry bag found in the Sniper's Nest

The FBI confirmed that the 3 types of fibers found on Oswald's rifle were a match to the 3 types of fibers found in Oswald's arrest shirt. The FBI's web site confirms that fibers coming from a different source is "extremely remote."
https://archives.fbi.gov/archives/about-us/lab/forensic-science-communications/fsc/july2000/deedric3.htm#Fiber%20Evidence:%20Assigning%20Significance
The rifle in evidence is the exact same rifle that Kleins sent to Oswald's PO box.
CASE CLOSED!JohnM