So were just talking about coins that haven't made it to an exchange then??
It seems like it would work in this senerio.

If the coin has already make it to an exchange, then what?? They sell it for the same price as the exhange price??
In this second senerio if the devs sold it for less than the exchange, then who would pay more on the exchange?
So the exchange price would immediately fall for the same price or most likely even less than the ICO