That would only follow if the evidence actually showed that Oswald ordered the rifle and handgun and used the rifle to murder the President and used the handgun to murder Officer Tippit. It doesn't. At least not by anything approaching a reasonable doubt. You're confusing conclusions based on the evidence (along with a whole lot of speculation and conjecture) with the evidence itself.
How is it this evidence does not prove this?
Because the paper trail is faked? Who faked it? How many people would it take to fake this? Who was in a position to assign the people to produce and insert the fake paper work in the appropriate location, to make it appear that this rifle was ordered by the same ?person? whose fake ID Oswald was found carrying?
Or do you believe that Oswald was not really carrying a fake ID? Even if this is so, officers would be needed to plant the fake ID on him and go along with the story, and other people would be needed to produce the fake paper trail that seems to lead to a P. O. Box associated with this alias.
In any case you seem not the least bit interested in producing a list of the evidence that is most likely faked, and the people needed to fake this evidence. This is one would likely do if they do not want to expose the fact that they believe in a large conspiracy.
You seem to use the cover ?Well, I?m not saying for certain there was a large secret conspiracy, so technically I am not a large secret conspiracy believer? while suggesting that there was.