So there are multiple ways to look at this. If another player enters the server for the 2:30 mins, and the original player reconnects back in time, what happens to the ringer who joined in? Why should he be punished.
We are working on certain features which will prevent people from rage quitting. But it will take a couple of weeks. In the meantime, we agree that if a player leaves/dcs a server and the game gets over before his cooldown starts, then he should not be given a cooldown, but we need to look at all possible angles so that no one can abuse this as well.