Since there was nothing currently flowing through those pipelines and no immediate likelihood of there being anything flowing through them any time soon, in the short term it doesn't hurt anybody. In the long term, it probably hurts Russia more. Europe will find the energy it needs elsewhere sooner or later. But since Russia will likely just sell their natural gas elsewhere, I'm not sure it really changes much of anything so I don't really see much of a point for sabotage other than to try to cause chaos and incite war.