it is not uncommon at all for clerks at USCIS or other government offices to not know what they're talking about, and to give out false information. Happens all the time on the 1-800 misinformation line. That's why we call it that.
Here are the instructions for the I-131 Advance Parole application. Give 'em a read: http://www.uscis.gov/files/form/I-131instr.pdf



