It seems there is a great reason for the Red Hessians and the SCRA to assist Rheinland against Liberty - great PR. The Rheinlanders seem more predisposed to start with, and those groups aiding in defending the nation shows a lot of positive traits in them. Would it be easier to get support from a populace that sees you trying to defend said populace or wholly ignoring them?
Anyway, once Rheinland is severely weakened but ultimately holds off the Libertonian advance, that's when they can sweep in and introduce vast governmental reforms. People will be more apt to change and get away from that oft-defeated system, right?