Occam's razor still has Russia responsible. Blowing up pipelines not being used, offering nordstream 2 as an alternative which would validate Gazprom's investment and also allow a force majeure to get Gazprom off the hook for billions it would owe if it didn't deliver on its gas contracts. Add to the fact Russia could blame the West for it. There is also one other element which Russia hinted at but countries like Norway and the UK heard loud and clear. If we can blow up our pipelines we can blow up yours. Which is a pretty powerful message.