It gets better. According to their website's FAQ;

. It is mandatory for all vehicles with a Gross Weight or Registered Gross Weight over 5,000 kilograms (five tonnes) to have a valid heavy vehicle transponder. For transport vehicles without a heavy vehicle transponder, the trailer licence plate will be captured by the video imaging equipment and billed to registered owner of the trailer licence plate. Heavy vehicles without transponders are also subject to a fine under the Highway 407 Act when stopped by Ontario Provincial Police (OPP) or Ministry of Transportation (MTO) Enforcement Officers. 407 ETR will also charge a $50 video toll charge per trip, plus all tolls, fees and interest. The monthly bill is due upon mailing.

It's a sure bet he didn't have the electronic tag, which are copmparable to the EZ-Pass used here over most of the northeast, and in Chicago. Without a tag he was bound to get stopped by the toll hungry owners of the 407. It's likley the only reason the guy got stopped.

Now, with this added info, here's the grand prize question; how the hell did this rig get into that situation?

As to the question about what they were about in Montreal, my guess is the cutter's torch awaited them.