Not true. The Elders never voted to excommunicate Leopold. Several people wanted to do so, but it was never done. The elders also offered Leopold a compromise that would have given him almost everything he wanted. He shot it down, accusing everyone of being corrupt, guaranteeing that the war started.
Leopold wanted this war. It was going to happen no matter what course anyone took.
You're right, there was no vote. He was just excommunicated.
