I believe it is time to draw this thread to a close.
Having been in this situation ... While it is the responsibility of the person passing to do so safely, it is also the responsibility of everyone - EVERYone - to ride in a manner that is reasonably predictable to others coming up from behind.
On a "normal" track - Mosport main straight isn't normal - the best thing to do when exiting any corner is to aim STRAIGHT for the turn-in point of the next corner. If that corner is in the same direction this will usually mean going STRAIGHT down either the left or right edge of that straightaway. If you anticipate overtaking another rider then do so in a manner that someone behind can expect - don't swing all the way to the other side of the track, a somewhat close but predictable pass can be better because it still leaves room for someone behind going even faster to pass YOU. If the next corner is the other direction (a right following a left, etc) then go STRAIGHT diagonally across that straightaway to your turn in point.
Mosport isn't normal because the back straightaway isn't straight. But, same idea. What you DON'T want to do, is surprise someone coming up from behind. Up until a little before the bridge, everyone is accelerating (or trying to) and is in view of riders coming up from behind. A little before the bridge ... wherever you are left-to-right on the track, is where you should be entering corner 8. Moving from mid-track to the left edge after that bridge can mean a very high risk to someone who was coming up behind and planning to overtake on the room they saw you leave them. So, commit to where you want to be on the track (left-to-right) well before you get to that bridge and STAY there until you turn in for the corner (at which point - ideally - everyone is going more or less the same speed for the corner).