The tree trimming was part of it. They also lost a couple of sections of high tension lines which really screwed things up. I don't think that had anything to do with trees.
Two of our friends and one of my wife's extended family were among the people laid off. They were pretty bitter an vocal about the under the table deals that were made to enable their removal. The companies didn't really care about maintenance and they underestimated how much could go wrong in that short a time. They still got their bonuses and rate hikes, so it's all good.