Their has been a lot of protesting of various pipelines in PA. It may be that this was something to do with that, this could have been someone stealing this to try and shutdown the pipeline building for awhile. Even the video attached to the article is from someone against the pipelines, but they don't seem to actually make the connection in the article to this possibility. It could also be someone just wanted to steal explosives for a nefarious purpose or not, but it would not surprise me if this was more of an attempt to sabotage/shutdown the worksite.