That's odd. I brought mine over in 2013 at Emerson, ND or Manitoba. Maybe you asked the wrong guys - did you talk to Americans or Canadians? It's very difficult to take a car from US to Canada, but rather easy to go from Canada to the US. I have not read the form in a long time, it may be different for post-74 cars with emissions control.
Getting the car registered in the state is a bit more laborious, at least in Texas. As long as I had the signed "title", which was just the license plate registration in Manitoba, then I had to have the Sheriff inspect it, then get a State inspection and insurance, and the title change and license plates went through fine.