They are only free from arrest, "when attending or traveling to and from congress, except in the case of treason, felony, or breaches of the peace". Their comments while on the Floor, or in a hearing, etc, are also protected.
LIVE: Large number of NYPD outside Columbia University; removal of terrorist 'solidarity encampment' imminent
A tall, armored NYPD 'Emergency Services Unit' just arrived at Columbia University; a ramp extending out from the top of the vehicle is allowing officers to easily get over the university wall.
NYPD is entering the university building through a window on the second floor via the use of armored vehicle.
President Trump [Hamnity]: I really think you have a lot of paid agitators, professional agitators, in here too…when you see signs and they're all identical, that means they are being paid by a source. These aren't hand-painted signs where people would go to their basement and paint something because they really believe it.. These are all signs that are identical. They are made by the same printer.
President Trump: We have to let Israel complete their war on terror. It's a horrible thing, but they have to do it, and they have to do it fast, and we have to get back to order. And people have to respect law and order in this country.