Now that you mention it, finding out if Oswald was a Soviet agent would be pretty significant.
I have always suspected that and the reason for the cover up wasn't because of conspiracy but due to a severe and epic snafu by Langley to track him and detain him. Remember, they had Oswald earlier (FBI) and let him go thinking he was just a bit nutty but didn't mean any harm. Also, the fact that he had a Soviet wife and made trips to Russia should have been a clear alarm bell going off to arrest him on charges of potential espionage but he fell through the bureaucratic cracks. These docs might reveal that. If so, the cover up was to contain the massive sh*tstorm that would follow but here at home and at large with cries for war. An assassination by a foreign agent of a president would have been a casus belli in most American eyes of that time and even today.
that's pretty much my take too