Make the hive smaller, and placeable only on ground.
Kharaa respawn on top of the hive, so a check by code has to be done to see if there is space above the hive at time of building.

Before the hive actually gets build, a majority of the Kharaa players have to agree with the location of the hive.

If the last hive dies, all Kharaa die immediately, to prevent games from dragging on.

someone has been playing II to much?

serious buddy, you know storywise hives need special locations in order to grow. This just won't work in NS. Perhaps NS2 or something