Well, the page you linked is the GUIDANCE. It is not the regulatory standard. Moreover, in the page that you linked, the only "regulatory" sign that is posted is the "ROAD CLOSED TO THRU TRAFFIC" which specifically outlines what the regulation is. The orange signs are guidance signs, meaning if a detour sign had an arrow that pointed to the right, you still have to option to turn left if you so choose.
You should be looking at this page as well Section 2B.48 ROAD CLOSED Sign (R11-2) and LOCAL TRAFFIC ONLY Signs (R11-3 Series, R11-4)
You can try arguing that you were not in violation but I honestly don't see how anyone could misinterpret that sign.

