Call it biased opinion. Call it logic. Whatever. Makes no odds anyway. Unless one chooses to believe Oswald didn't take a rifle into the TSBD.
Oh but it makes odds. This is some logic for you;
Without the paper bag being big enough you have no way to demonstrate that Oswald ever took a rifle into the TSBD.
So I guess you just choose to believe that Oswald brought the rifle into the TSBD regardless of the fact that there isn't a shred of evidence for it...