There’s no grounds for revoking their visa based on constitutionally protected speech. The courts have ruled many times that immigrants have the constitutional right to freedom of speech, assembly, due process, and equal protection under the law.

Either we scrap the constitutional rights and the courts reinterpret the constitution or these people deserve a day in court if the government feels they’ve done something bad enough revoke their visa. And that thing legally can not be what they said or what protest they attended. If they were arrested for say breaking a window at the protest, that’s a crime and they could be charged, put on trial, convicted of that and have their visa revoked. Because of what they did and not what they said.