I don't agree with this. That had very little effect on the war. Yes, Caitlin kidnapped Tyrion because of it but even that didn't get it done. IMO it is Joffrey who is most directly responsible for the war, by beheading Ned Stark. Up until that point things were just tense, and could possibly have been salvaged without open war. Most likely by holding Ned hostage against action by Winterfell.