Excellent question! Always glad to see players interested in the story and plot behind a campaign.
The clue is in the briefing:
...reports indicate that all necessary components have been made available to the 8th Battle Group and are being rushed to Marnakh, allegedly by GVTI courier.
I've added the bold. There is another clue when the GTC Pallas arrives:
This particular vessel is one of only three attached to GVTI, but we judged your situation important enough to deploy it to the Marnakh system.
GVTI is not only aware of the expedition into Marnakh, but is following it with great interest and has even gotten involved. They place a high priority on the exploration of this new frontier because it could provide solutions to a number of very complicated problems plaguing the GVTA. At the same time, the situation is extremely tenuous due to the state of the Knossos portal. So the GVTI engaged in some political back-channel maneuvers to persuade the Gateway Project and Delta Serpentis to drop their objections.