Oh my God! That sucks! Fight it for sure. How are we supposed to have registration/insurance if they won't register/insure it? Have a read through this thread: http://motorbicycling.com/f17/ontari...info-6044.html
, Rockenstein & The WANDERER(especially) make some good points for you to bring up in court. There was one example of someone able to register his bike through a form, and insure it. But after an accident the insurance company proved that it wasn't actually a motorized vehicle so they wouldn't have to pay. There's gotta be case laws already in Ontario, or something similar.
You should pm them for advice!
The mto and hta are too vague anyway, technically they're not legal or specifically illegal by current standards. I'd plead ignorance if anything. I've tried to register my bike in Kitchener(i'm in Wallaceburg nowadays) and they told me they can't, and just to ride it.
Can I ask why the Officer stopped you? Doing a wheely or something? heh heh. I've driven past many cops too, and they just check it out and move on.
Good luck Mark.