No, he's right, according to the rules on some "official" websites, and some posters on this forum, even residents of Canada/Mexico should have a B2 visa if they intend to spend more than 90 days in North America. You might recall all these discussions we've had here about whether exchange students and long term visitors of Canada/Mexico need a visa or not. My opinion, and that of many CBP officers and consulate staff I've spoken with, and many many sources I've heard from, is that a visa is often not required. The only thing residency in Canada/Mexico buys you is that you can officially travel there on a one-way ticket via the US. For reference, below are the official rules the airlines go by. As you can see, they will allow you to travel to Canada/Mexico via the US on a one-way ticket even as a non-resident as long as your stay in the US is a transit -- this is not quite in line with official US immigration rules. As with the immigration rules, the airlines seem to apply these rules at their discretion. I have written before about Icelandair who are very lax about allowing people to travel to the US on one-way tickets on the visa waiver.
IATA rules used by airlines:
Visitors must hold return/onward tickets. Exempt are holders of a valid US visa.
A return/onward ticket (or electronic ticket record) must be to a final destination country other than Canada, Mexico or contiguous (adjacent) countries or territories situated in or bordering the Caribbean Sea . If passenger holds proof of residence in, or is transiting the USA to such a country or territory, an onward/return ticket to that country or territory is accepted.
Compare with information from US Embassy:
If entering the United States by air or sea, you will qualify for travel under the Visa Waiver Program (VWP) if you are holding a return or onward ticket. If traveling on an electronic ticket, a copy of the itinerary must be carried for presentation to U.S. immigration at the port of entry. Note: Travelers with onward tickets terminating in Mexico, Canada, Bermuda or the Caribbean Islands must be legal permanent residents of these areas.