Heh. So if nodes are based on the spacial geometry of the universe, solving Einstein's field equations would provide us with a nice extra perk, wouldn't it?
But seriously: It makes sense that nodes must be anchored to things with mass, or else they wouldn't be following the galaxy as it zooms around and around in circles at mindbreaking speeds. The only force we know of that is a direct result of the presence of mass, so it isn't too far of a stretch to believe that subspace is related to gravity.
That said, what does this have to do with tactics? I guess that you can argue that one can blow up massive objects like suns, moons, or planets to form/destroy/move nodes to make situations that favor you. Regardless, it could be a cool plot device to use in a campaign, as long as the means to blow stuff up like that isn't ridiculous.