I don't buy terrorism either unless it was (as has been speculated) a dry run:
* seeing how much damage could be done with a rifle,
* how long it would take,
* What steps are taken to mitigate the damage,
From that one could possibly analyze how much bigger the real attack would need to be in order to achieve whatever goal is planned.

But that's all speculation. As a single act calling this terrorism is a stretch, but cutting fiber cables prior to firing 100 shots "to "methodically" make transformers overheat and shut down" seems like more than a couple yokels out for a hoot. It was well planned apparently with prior knowledge of the substation; I'm surprised they left their brass.

Hope whoever is investigating this has more than 100 pieces of brass.