There is a plenty of class which a player can select. For new players, they need time to check what is special for each class by selecting class info. It takes time at the beginning. And if a player is using for example grenades hydra, tank or even sawns, believe me, that extra spawn zone hitpoints is nothing. So spawn kill is not allowed.
If a spawned player moves even a little bit, standing but using guns, doing any noticeable action, kill him.