Uh, no. Every Marine, no matter what their MOS has to qualify with a rifle. Cook, airplane mechanic, machine gunner. Doesn't matter. The Army has lower standards, not opinion just fact. Marines have been known all throughout history as being infantrymen first, their MOS second. The Army has no such distinction. One year of rifle competition doesn't make a trend, and at that level half an inch can make the difference between winning and 10th place. Your example is pretty much invalid because it ignores almost 250 years of history.
Saul is a poor shot all around, it's been stated multiple times that he isn't the best choice to have when something needs shot.