How can you have "no idea if Oswald actually handled that bag" if his prints were found on it?
Were his prints found on it? We have the word of an FBI expert, and a police expert supposedly working from photos that were later published and didn't show much more than blobs. I have numerous books on fingerprinting, going back to the forties. These books show readily identifiable prints and matches. The matches presented in the WC's volumes, on the other hand, are little more than blobs. They show nothing. The government has had more than fifty years, moreover, to publish proper photos of the latents, alongside Oswald's prints, and has failed to do so. And the FBI has refused to releases its photos of the trigger guard. So, no, the fingerprint evidence is not a done deal, far from it. Every print connecting Oswald to the sniper's nest or rifle is suspect.
Now, do I think the FBI flat-out lied in its identification? I'd say no. But the provenance of most every print is suspect, starting with the palm print tore from Box D and ending with the palm print purportedly lifted from the rifle.