He must have been more familiar than he claimed. He would have to know a few things: what the throttle is, what the mixture is, what you have to do with each to make the engine run, what the master switch is and that it has to be on to start it. He had to know that you steer with your feet on the ground.
If he knew that stuff, yeah the story could be true. However, it was also night time. That means he probably had to know how to turn on the airport lights (key the radio switch), what frequency it needed (may have already been tuned in), and where that button was. Without the lights, the airport would have been a black hole, of course the lights may have been on already.
The other problem is how different it looks at night. If he really knew nothing, chances are he would have gotten lost, not gone back to the airport.