[Alneyan]

You *cannot* use intelligence if your opponent has closed all the wormholes leading to his systems, as you will lose contact with this Empire if there is no wormhole connection between at least one of your colonies and one of his. And without contact, you cannot launch intelligence projects against this Empire.

Even if you put a ban on full turtling, you might encounter a situation where an Empire has only one wormhole leading to all its systems. You would then be able to blockade the said wormhole with all your ships/units, making a breakthrough almost impossible. Twenty thousand fighters, bases and the usual defence taskforce of warships would pack a lot of firepower, and it would be possible (and even easy) to make such a situation by creating ten wormholes in all your systems. You merely need some time to do so, but not that much in fact. On the other hand, building the System Shielding facilities would take a lot of time given how expensive this facility is both to research and to build.