When I was stationed in Washington DC in the early 1990's I was at The Office of Naval Intelligence, located in Suitland, MD. On the same facility, is the Census Bureau. My wife got a job there, in the Year 2000 Census office. These were the people coming up with the questions to put on the 2000 census form.
Given that the census bureau is an unbelievable government bureaucracy, there is no way possible that the worker in Moab, Utah would ever get an FBI agent to come out and even talk to you, let alone come arrest you. I would have done the same thing. Only I would have asked them if they wanted the phone number for the FBI and offered them a phone to call and make the report.
Yea, go ahead. Call the FBI. Here's a phone.