That language vastly expands potential liability. If a website knows that its services are being used to somehow assist in sex trafficking,[1] the website could be as culpable as the persons getting paid to coordinate the shipping of sex slaves. It's completely bananas.
Here are the sponsors:
Rob Portman (R, Ohio) Richard Blumenthal (D, Connecticut) John McCain (R, Arizona) Claire McCaskill (D, Missouri) John Cornyn (R, Texas) Heidi Heitkamp (D, North Dakota)
[1] It's pretty much impossible to run a website that allows people to communicate that isn't used for illegal purposes. For example, GMail is definitely used to facilitate a wide variety of illegal conduct. Up to now, for criminal liability to exist, you had to go beyond knowing that your service was used to assist criminal activity to taking special measures to assist that criminal activity. This bill basically lowers the standard from "having intent to assist the illegal activity" to "knowing that what you're doing will somehow assist the illegal activity."