Wrong. The "protesters" were conducting counterintelligence to locate where ICE was operating. The plan was to disrupt the operation. Like it or not, this is against the law. Period.
18 U.S.C. § 1505 - Obstruction of Federal Officers (this includes ICE itself - obstructing or interfering with an ICE arrest is a crime)
18 U.S.C. § 118 - Obstructing, resisting, or interfering with federal protective functions
Those other two laws seem like an even weirder fit for the fact pattern in this subthread.
If "ICE vehicle has been identified, everybody go there" is followed by mobbing vehicles, blocking movement, inducing agents to disengage, or warning targets to evade arrest, that crosses from protected speech into actionable conduct.
See Brandenburg v. Ohio (https://www.oyez.org/cases/1968/492)