There is a pretty strong argument, I think, that it is impersonating a police officer, when a federal agent implies that they are NYPD. Federal personnel are allowed to represent themselves generally as police or law enforcement, and have been doing so for many years. What could set this incident apart are two factors: First, if the agents described themselves as NYPD in particular, that moves from vague insinuation to direct impersonation.
A federal judge on Friday ordered the Department of Homeland Security to pause immigration arrests at courthouses across Northern California and in Pacific islands, a ruling that could still be appealed by the Trump administration. Since May, Immigration and Customs Enforcement agents have arrested hundreds of people at routine check-ins and court hearings in San Francisco, Concord, and other immigration courthouses across the state and country.