But if this ad is directed at me, and I also play poker with some guys in the mortar battery every week, and I genuinely believe that those guys will provide fire support whenever I ask them, even if I'm a lowly grunt, then what does it matter who's platoon leader?

Actually, I can think of a reason: It's best if the platoon leader knows these guys too, since the platoon leader will actually know of more situations than I will to call on these guys. It's the "better-than-average chance" that shouldn't affect anybody with a genuine belief in Matthew 7. According to the Bible, the chance is either 1 or 0 (or so close that you might as well round it off), once you know whether a person is Christian or not.