Earlier quoted context omitted.
Sure but they'll make your day extremely unpleasant before deporting you or if a USC letting you in. A few things that's happened to me as a citizen after invoking right to remain silent to CBP 1) Told I could not enter the country. Held up for 3-24 hours in holding areas. Officials come in and claim they will revoke my passport under "national security"-esque grounds. Lots of bluffing and huffing and puffing. Diesel…
To clarify: CBP is Canadian Border Patrol and you are a Canadian citizen re-entering Canada when this happened?
Probably US Customs and Border Protection.