Trading on inside information has that causality going on the other direction. It's them picking what stocks to buy depending on what laws are being most argued for/against. Every stock looks the same from their POV, and there's no reliable mechanism for making them prefer one law over another.

The GP is right. It's campaign contributions, career rolling doors, and direct payments that make them pick one law over another. Inside trading only let them directly steal money from the population with no strings attached.