Note: This is all my speculation, if you disagree, make your own speculation blog
So, let us for a moment assume that SK never plotted to hit Rose after this war, and that SK never hit Vanguard.
In this universe, SK and Guardian both declare on VE first, just like what happened here, only that SK never hits Vanguard.
VE, then naturally calls on their allies, BK, WWF, tS and Cornerstone, and they both declare war on Guardian and SK.
The war then expands, as Guardian calls on Vanguard, DEIC, and Mensa, which all hit VE, tS, and BK.
Basically, at this point, SK and Guardian can call on a number of alliances: TEst, Rose, US, and possibly even UPN and BoC if DEIC could convince them to come along. Even without them, this war would have been pretty even.
In all honesty, I think plotting against Rose was the nail in the coffin for SK this time, causing them to get rolled by almost everyone in Orbis.
Even if the plans to roll Rose weren't exposed, I assure you, many many people would be reluctant to ever get close to SK after watching what they did to Rose.
This war could have been close and possibly won by SK, had SK not plotted, however, SK was either too paranoid or power-hungry that they decided that they needed to roll Rose.
This is all I really have to say about this war in general. And my advice is, if you're allied to SK, drop them, because I don't trust them as far as I could throw them.