15(6)A person driving a vehicle shall not drive the vehicle in such a manner so that the vehicle occupies space in 2 traffic lanes
(a) except during the act of passing another vehicle or changing lanes, or
(b) unless road conditions make the use of a single traffic lane impractical.
Based on the picture and the fact this ticket was issued after and no peace officer present, I would choose two routes.
Got to JOP and plead guilty to a lesser offense of a traffic lane violation as you believe you were not stunting but did indeed straddle the two lanes.
http://www.thepointman.ca/offenses-demerit-points.php
Or take a chance, go to court on this, hope the witness doesn't show up. Then it's quashed. Or if they do, argue the definition of stunting and what zipdoa said, that you were not the operator of the bike at that time. Bring friend's that have your same stature.
115(2)(e) perform or engage in any stunt or other activity that is likely to distract, startle or interfere with users of the highway.
If the witness is the photographer in the picture you posted, they're using a phone while driving.