This comment is not really correct
1. The misappropriation theory of insider trading covers anyone who trades on material non public information sourced through a trusted relationship regardless of any fiduciary duty to the company. For example, if I tell my personal attorney a non public fact about the company I work at, and they trade on that information, they absolutely can be found guilty of insider trading despite having no relationship to the company at hand.
2. Congress is explicitly covered by insider trading law, which was affirmed in the STOCK Act of 2012. The fact that they’re rarely indicted has more to do with the legal and political challenges associated with doing so, not the legality of the act.