I wasn't present at your conversation with the PA-28 pilot, Genghis, but I don't think you should read too much into the attitude shown.
Presumably he'd not long since landed, may have got something of a shock close to the end of the flight, and may have been feeling somewhat embarrassed. He was then approached and confronted by two strangers who... well I don't know exactly how you phrased it but I read into your comments that you were assertive if not overtly confrontational.
In an ideal world of course, you'd all have analyzed what had happened rationally, with perfect recall as to the facts. In the real world, people tend to take entrenched positions, particularly when accusations start flying. You may be quite right to be aggrieved, but in the long run you may find that taking a magnanimous attitude to the perceived transgression reduces stress levels for everyone, including yourself.