The only reason that the Harvest Joy was destroyed is that there was a squadron of Mannerheim BC (or Heavy Crusiers, I didn't go back to look) picketing it right on top of the exit lane. The ship came through, they blew it to bits before it had any idea there was anyone waiting.
The Mannerheim force on station rotates it ships up to the exit lane.
Why are they there vs. ships of the Alignment Navy was probably because the Alignment wasn't building (that we knew of) conventional warships and wasn't training crews for them. Not clear if Mannerheim is building any of it's own ships or getting them from Technodyne or similar builder. The Alighment appears to be building Streak Drive ships, not clear -other than the Spyder Drive ships- what hypercapable shipping it is building.
When the Harvest Joy didn't return in a reasonable amount of time, there were only two serious theories about what happened. One was that they had found the 2nd wormhole that destroys ships. The other is that something happened to the ships equipment such that they couldn't generate the Sails and, if unable to manufacture replacement parts, would have to attempt to come back via hyperspace. Of course they could have suffered any one of a number of engineering casualties and be alive but not able to go anywhere at other than perhaps non-hyperspace travel.
The reason to kill any non-Alinement ship comming though is to keep anybody else from exploring the other side of the wormhole and find the network that the Alignment us using. Of course, at this point there seem to be various sensors parked out by the Torch Wormhole to monitor it and those would also not any ships using it from either end. So, the Mannerheim guard force is going to have to get it's releif from ships entering the hidden network somewhre elce.
That just might be a way for the GA to pick up the thread of something odd going on if squadrons of Mannerheim warships are noticed in places far from home and over time.
