Interesting game you're playing. If you understand what he's saying, and have no reason not to trust him, you wouldn't need to ask why I THINK it's important.
Happy to call your bluff.
What Holmes says is no slip no number to search. Without a slip in evidence there's no reason to believe that search ever took place or that Oswald bought that money order.
That the money order was signed by Oswald (under the A J Hidell alias) has been established by handwriting analysis. No matter how you try to argue around that, it's the 900 pound gorilla sitting on your puny objections, crushing them under it's weight. At that point, the USPS stub carries no real meaning as evidence that it was used to purchase the rifle. It's usefulness was limited to finding a PMO for the right amount of money at the right time and using the serial number on the stub to track down the actual money order.
