There was only the one node from Sol anyway. We speculate that the others were too unstable to use anyway, because FS1 is riddled with so many background holes that it's a wonder it can stand upright at all.
The Meson warhead was only intended to destroy the Knossos portal, as they reckoned that without the portal's stabilising influence, the node would collapse anyway. They were wrong; while being stabilised by the Knossos, the node had become stable in its own right, and no longer needed the portal to keep it usable.
I don't think you can collapse subspace with an explosion in real space anyway.