From the indictment, he's being charged with the following:

* Unlawful Use of Confidential Government Information for Personal Gain

* Theft of Nonpublic Government Information

* Commodities Fraud

* Wire Fraud

* Engaging in a Monetary Transaction in Property Derived from Specified Unlawful Activity

https://www.justice.gov/usao-sdny/media/1437781/dl

It's rather obviously illegal to leak classified intel by taking public actions based off of it... that's practically the meaning of the word "classified".

Not true, they lobbied very hard to be regulated under the CFTC because of its more relaxed rules

Polymarket isn't being accused or charged with wrongdoing.