Congress did though, explicitly. There is a

provision within the Immigration and Nationality Act that exempts noncitizens facing deportation under the government’s “foreign policy” provision. The exception, known as Section 212(a)(3)©(iii), says that an individual cannot be deported under the “foreign policy” provision cited by the government if their “past, current, or expected beliefs, statements, or associations, if such beliefs, statements, or associations would be lawful within the United States.”

Source: https://theintercept.com/2025/03/13/mahmoud-khalil-legal-free-speech-deport/

Now that’s the problem with having secret police who wear masks, don’t show warrants, and refuse to give their names, isn’t it?