Aren't they always? "Where's there's smoke, etc..."
It's all a matter of how far the cancellations get. If a moderately influential party (one alliance or several) can stop the dominoes from falling, war can sometimes be avoided.
On the other hand, recent history has shown us quite the contrary - it all depends on context. For example, Pacifica came out and said that they would never war on Polaris, which in another situation might have closed that whole issue right there (at least for some time). Obviously, there were circumstances that made war inevitable - this is not a debate on that.
Finally, my favorite war rumor will forever be the floating rumors in Crazy-World about the Unjust Path Remixx where they all pull a Viridia and return to fight one last battle.
I can see the propaganda already - unfortunately for that rumor, many of those players have either joined a sanctioned alliance.. or have left the game in the past year. Still, it's fun to speculate