No, it isn’t. If the track is concave, driving the convex closure of the track shortens the distance travelled, decreases the amount of turning to do, and no corner will become tighter. That must mean the convex closure is faster to ride.

I guess that’s why the red cones are there. Passing them on the wrong side must lead to a steep time penalty or immediate disqualification.

Also, I would think that, in a really tight turn, you would have to slow down so much to stay on the track that overshooting the turn without braking as much is faster (I think the video shows that in the last corner of the round, at the right edge of the video)