A fair question - no snark taken.
Making up my own reason doesn't make it the 5FW - it's a war IM3I. Not completely opposed to that as there are things I don't use IM3I (Empress Wave, grandfather, the ancients - too much meta-game for me). There is a lot that I do use, and I like to stick to the 3I as much as possible. So far, nothing I have excluded has made that much of change (IMHO of course

). Maybe I've just been lucky with my players.
So yes, I could create my own reason(s) for the Zhodani to start the war. I could even call it the 5FW. But something that is - or could be - such a fundamental game-changer for the 3I is turning into a mixed bag of resources. I feel I need to wait until everything is published before I can entertain how to work it into IM3I (which is my current plan).
Hope that helps to explain it.