You know what? Wouldn't this be better as a Gate Starbase?
I thought we already said "no stuff that prevents starbase usage for certain races"
Remember? my supergun idea was rejected...
but otherwise, placing a military starbase at your end is feasable, because it can't shoot so you'd have to have guard fleets there all the time.
Maybe, if you destroy the wormhole generator, you cause serious damage on both ends (think planets rendered radioactive/class-0, suns destroyed, starbases imploding, engines shut down), but if you just turn it off, the ship just gets destroyed.
Just like how the arceans destroyed the drengin when they came through the stargate with a bighuge fleet... you just turn it off and they can't win, no reinforcements.
It would be the same, yor come through, you turn it of in fear and blow them up and then turn it back on. There has to be some MAJOR penalty.