MP, Instant, 34
I bid this hand as a bit of an experiment. I was seriously concerned at the prospect of 3N being passed, and if really trying to win I would not try it, but I was curious.
A balanced hand with lesser strength would open 2N, so notwithstanding the meaning assigned to the 3N rebid I feel that it is the right technical bid for the hand.
The assigned explanation provides South with as few as 19 HCP. But a hand of such weakness would have compensating distribution. Although North is a passed hand it would appear right for South to show distributional features.
In F2F games I am accustomed to positive responses to 2C being forcing to 4H at least, and in some to 4N.