The last time Nader took US Air to court, or whatever they were called back then, it went all the way to the Supreme Court, and we now have bumping policies in place.
I'm sure when he phoned them up and spoke to their legal people (as mentioned in the story) they heard the words Ralph Nader, Court, and said you know, lets just shut him up this time like we should have done the last time.
I also tend to think if I called them and somehow managed to get to their legal team and said "Look, I bought a non refundable ticket, and it was going to rain, and I drove instead, I'll take you to small claims court if you don't give me a refund" they would be laughing too hard to respond.
This is not a story about taking a big airline to small claims court, it's a story on if you are famous enough to be an actual threat to them, they will back down.
Most of people who buy tickets on US Air do not fit into that category, and they would say go ahead, take us to court.
If his flight did take off and land on the day it was scheduled, he should not have gotten a refund (interesting the story does not mention if the flight did fly that day or not), unless US Air offered travel waivers. But he did because he's Ralph Nader, not because of the small claims threat.
Nader is a huge advocate of harassing companies in Small Claims Court. In a documentary where somebody opened a bank account with a dollar, and then proceeded to buy a few things causing overdrafts to rack up the fees (for the benefit of the film), nader said
If a million consumers filed a million small claims court actions a year against the banks, the banks would either try to abolish the small claims court or improve their performance."
He's a champion of advocating people agree to something, then sue when they break that agreement.