Congress sometimes includes an exemption for themselves from some crimes. Others are excused by the Constitution:

> The Senators and Representatives shall receive a Compensation for their Services, to be ascertained by Law, and paid out of the Treasury of the United States. They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.

Explanation:

https://constitution.congress.gov/browse/essay/artI-S6-C1-2/...

As for insider trading:

> The law prohibits the use of non-public information for private profit, including insider trading, by members of Congress and other government employees.

https://en.wikipedia.org/wiki/STOCK_Act

He was charged with "unlawful use of confidential government information for personal gain, theft of non-public government information, commodities fraud, wire fraud, and making an unlawful monetary transaction.". Supposedly, unlawful use of government confidential information could also be applied to legislative and other people in the government