Can't blame them. If SF starts hostilities now and Luria and the League strike a truce any time soon, they're pretty much screwed, given the difference in nobles count.
If SF declares war on the League, they'll become a much easier target for Morek and Astrum than Luria is. Even D'Hara could strike at them easy.
The way I see it, if they do that, they will die, Barca will die by the distraction they create, Luria would grow a bit, and then we'd be back to the old war.
Balance's Retreat could make for a new Barca, though...