they probably didn't do anything illegal.
This was my first impulse, but the STOCK Act seems to be pretty clear. I still share some of the skepticism, though.
i definitely haven't delved into the details of the restrictions of insider trading or on what they knew at the time of their trades. but, just based off of three of them taking the same action, i'm guessing they were within the letter of the law.
like, if the briefing being discussed consisted of publicly available info, i'm pretty confident it doesn't matter if the senators were publicly saying - "hey, country, don't panic about this unimportant publicly available info" and then panic selling everything they had in the market.