Wherever the official storylines goes, I still think there's an obvious compromise.
I think of all the Sith who remained Imperialists despite the galactic truce. I'd doubt a mass culture shift to be unanimous, even with a common enemy in Zakuul: surely there'd be Sith who bent the lines of ceasefire with the Republic. There were certainly those who bent it during the "Cold War." What of the Sith who see the new Empress as flimsy at best, and are biding their time (or actively supporting) for a coup or regime change.... some might seek to climb the ladder of chaos, some might seek a return to old teachings or war-time, some might support this New Imperialism yet want different laws/leadership... etc. etc.
Upon returning to the game, I see Imperial jurisdiction isn't the same as it was with several Spheres and hierarchies to monitor every citizen's move. Perhaps this lends greater freedom to Imperialists? I think a secret division, or an old team that reconnects, or even a loose alliance of contacts would be feasible; I think of an archetypal team of underdogs that (even unsuccessfully) works to nip away at leg #3,674 of their great overlord. Any way, I love that you're targetting a sort of rogue audience. Since I think there's plenty of IC rogue audiences still lingering in the Empire, I say a separate timeline isn't even needed!
Any ideas about the type of RP a group like this might work toward?