Yes, because Russia is temporarily sanctioned. The moment the sanctions are lifted, Russia will still have the cheapest prices due to proximity and infrastructure. And Europe, of course, would resume buying from Russia, although they will try to secure better backup solutions in case of a future incident.
Blowing up the pipeline makes sure that gas flow will take a considerable time to resume. This gives leverage to alternative suppliers to negotiate for long-term deals with EU. With long-term deals in place, it will take several years for Russia to regain its dominant position in the European energy market.
> And finally, there is a huge risk involved for the US.
What risk? The Baltic Sea is controlled by NATO. It's fairly easy for the US to find or create a window of opportunity to carry the operation.
The risk is, if the US ever gets caught, then we'd significantly burn our relationships with our European allies. How is sabotaging our geopolitical position in exchange for oil companies making some extra bucks worthwhile?
Exactly: if.
> we'd significantly burn our relationships with our European allies
But let's say that the US is caught red-handed. I doubt the consequences will be anywhere close to dire for them. See what happened when CIA was revealed to be spying on chancellor Merkel (hint: nothing). As this action will not be directly against any EU nation, significant reactions are very unlikely.
At least a few EU countries would probably align with the US, vetoing/dampening any centralized reaction from the EU. I am aware of at least one EU leader that wouldn't mind undermining EU in exchange for an invitation to the USA and a photo-op with the POTUS.
Some countries will be secretly mad, yes. But they won't have the option to stay mad for long. At the end of the day, US would even find their geopolitical position reinforced because of the fragmentation inside the EU.
What would be that moment, though? When they pause killing? When they decide to start peace talks? Frankly, I find it hard to imagine everyone* gets back to business as usual after everything that happened. Maybe if Russians themselves killed Putin and at least apologized it would be a good starting point to consider talking about potential lifting of sanctions.
* except Hungary
There was no gas flowing through the pipeline anyway.
Ukraine is already winning the war.
European states are already looking to buy gas from anywhere but Russia
And finally, there is a huge risk involved for the US. If any evidence ever surfaces, the US may lose the trust of most of its allies. I don't see why taking this risk would be justified.