You missed the part where Oswald wouldn't tell the cops where he bought the firearm in Fort Worth. So that claim remains, well, worthless..
Who says that Oswald wouldn't tell the cops where he bought the revolver?
And, if he did, what's wrong with a suspect saying "you are the cop, you figure it out"?
You don't conduct an investigation or interrogation without verifying if what the suspect said is true or not.
The FBI spend weeks checking some 400 dry cleaners to find out where Oswald's gray jacket came from
Nobody made any effort to check out the origin of the revolver. Go figure