I see a bored stiff squaddie who lightened up his stag by providing a bit of light entertainment to what sounded like a clearly appreciative audience.
The kids we hear on the soundtrack will remember that more than they would an ordinary Guardsman on sentry duty, and probably tell their pals.
With that kind of initiative and situational awareness the Guardsman's probably just the kind of guy you'd want around when the bullets are flying.
Just a thought.