I don't think there's any evidence this was state-sponsored, or even state-approved, but "oh there's better things to do" is not a good argument in the least.
Also shouting 'No Evidence' is a typical tactic the propagandists use to cast doubt and muddy the waters; surely the attackers would love to see what evidence is available, so they can adapt - that's why evidence is largely kept private.
What makes you think propagandists on our side would never use lack of evidence to make whatever they want up, and cite your exact reason as justification?
This is medium-scale hooliganism in the sense that the end result isn't going to accomplish more than a dedicated idiot with a toolbox, and a grudge against gas pipelines couldn't achieve. IT will clean things up, operations will resume, life will go on.
Not to mention that this gives the industry another, rather low-stakes kick in the ass to take IT security seriously.