Originally posted by IceFire
Maybe there's a difference with destabilizing the node from one end or the other?
I tend to go by this theory. If you blow up a node then the subspace corridor collapses. Thing is we don't know how quickly this happens. The GTVA were trying to get all their ships out of Capella but the last thing they'd want to happen is for the shivans to start swarming into Vega after them.
Now assuming that the subspace corridor doesn't instantly fail (it's a huge assumption but lets see where it takes us) then the logical place to shut the door is at the Capella end. That way you can get your people into the corridor and close the node. They can then travel down the corridor and exit out the other end.
If on the other hand you try to close the door at the Vega end you run the risk of something faster than the ships you have in the coridor getting in. That leaves you with two dreadful choices. Blow the node and kill everyone in the Corridor or fight the shivans swarming into Vega and hope you can hold whatever they've sent through the node until you can get the civies out of the corridor.
A second reason is that if you send the Nereid towards Capella it could act as a backup should the Bastion have failed. If the Bastion didn't make it then pluging the Epsilon Pegasi node is probably more important for the simple reason that the Meson Bombs are made in Vega and there may be more in that system. So you'd only have to fight the shivans for long enough to load some onto transports (or another decomissioned Orion) and send it it into the node.
To plug the Epsilon Pegasi node on the other hand would also require you to get the bombs ready and then jump along this route :
Vega>>Deneb>>Sirius>>Regulus>>Polaris>>Epsilon Pegasi. You'd have to fight off the larger number of shivans who made it through in that time too.