When you gotta go you gotta go
, but that usually doesn't extend to flying a plane.
While it's unclear exactly why this plane is stopped on the side of the road, presumably this pilot has just made an emergency landing on the highway. Whether it's for an issue with his plane or his bladder is a different question. Small engined planes make emergency landings on public roads fairly frequently, but rarely does a pilot exit his plane with such nonchalance that he can stroll to the shoulder and relieve a different kind of pressure.
Perhaps the stress of an emergency landing loosened up this guy's bladder. But just maybe, when faced with the choice of peeing in his pants or his cockpit, he chose a third option, and put his plane down with balls of steel and a bladder of paper.