Trevor's Star through-traffic during open hostilities
However, there seem to be some additional misconceptions floating around. Specifically, discussion as to whether or not the Trevor's Star terminus of the Manticoran Wormhole Junction was used during the period when Trevor's Star was held by the People's Republic. The answer is that, yes, it was. Don't forget that the Manticoran Wormhole Junction is something like two light-hours from Manticore-A. That's enough "strategic depth" for the Star Kingdom to feel relatively confident that even an invasion fleet which managed to take out all of the Junction's immediately adjacent infrastructure and fixed defenses could be intercepted by Home Fleet well short of the planets of Manticore or Sphinx. The reason I make this point is that I want it clearly understood that what we're talking about here is not a dagger pressed to the throat of the Star Kingdom, but rather more analogous to allowing neutral commercial traffic to pass through a vital international waterway (like the Arabian Gulf) in which one belligerent has a huge strategic interest. I'm obviously not saying that no precautions were taken, only that procedures could be worked out.
Remember that each terminus has its own separate arrival and departure lanes. (This has been referenced in the books.) That is, an inbound ship is not going to come remotely close to running into an outbound ship, so sequencing transits is most important - from a safety perspective - from the departure end, not the arrival end. Second, everyone on both sides knows exactly where any ship from the other side is going to arrive. Third, I never said there were no warships anywhere in close proximity to the emergence point; I said the forts were well back, outside energy range. Fourth, no one has ever said at any time that the Trevor's Star terminus served only Havenite commerce. In fact, if you look at what happened to Haven's right of transit following the events in On Basilisk Station, there wouldn't have been much point in my specifying that Havenite ships had been denied passage if other ships weren't continuing to enjoy passage.
So here's what happened, people. After open hostilities began, additional restrictions were placed on all passage through the Trevor's Star terminus of the Junction. Light warships were placed within energy range of the emergence point, and it was made clear to everyone involved that any ship coming through which did not immediately follow the procedures on which they had been thoroughly briefed before being allowed transit or failed to conform with any additional orders from traffic control after making transit, would be fired upon and destroyed. Stringent inspection procedures were put in place, which included stem-to-stern customs inspections, searches for weapons, documentation checks, etc. The precautions weren't perfect (by the nature of things there are no perfect precautions), but they were more than sufficient to deal with the potential threat which could be represented by any single merchant ship (or Q-ship) making transit, especially when the ship in question was two light-hours away from any of the Star Kingdom's inhabited planets. Those inspection procedures were also applied to ships departing through that terminus. Cargoes were subject to inspection, items which the Star Kingdom had declared contraband were subject to seizure, vessels suspected of intending to violate Manticore's restrictions on what could and could not pass through the terminus were subject to seizure,, etc. Traffic with diplomatic immunity or which belonged to one of the major service organizations was allowed to pass without inspection, but only aboard very small vessels which were under observation the entire time. The major defensive works, on the other hand - the forts - were far enough back to be out of range in the event of any insane mass transit, and to have enough space between them and the terminus (space equaling reaction time, in this case) to be able to take at least some time analyzing the threat before opening fire. But the entire time, there were light warships, inside the volume of the Junction itself, to do to any suspicious vessel exactly what the battlecruisers did to [spoiler removed].