In addition the bad-trigger scenario would imply that the explosives and triggering mechanism remained in place on the remaining pipe, which would require the US to rush there to remove them or trigger the missing one to avoid terrible diplomatic consequences if the unexploded device were to be discovered.
Second, those terrible diplomatic consequences probably happened, behind the scenes (and weren't that terrible, because no one really wants to denounce the US in the middle of the Ukraine war). I'll remind you that both Sweden and Denmark claimed nothing other than sabotage could be concluded, and closed down their investigations and classified the heck out of the details. Feel free to make freedom of information requests to them, so that you can get those "national security interest" refusals.
Odds are that the US didn't directly admit anything to them, but strongly suggested they shouldn't look too closely or be too specific in their statements, and that those states were quick to comply. And probably cleaned up well enough that there was nothing left for the Russians to find, in the case that they should run their own investigation (although, Russia can't run a real investigation to save their ass, they're too used to have their conclusions dictated to them, so I wouldn't worry if I was the USG).
And the rest is all putting the cart in front of the horse. Would it look any different if Russia (or anyone else) were the culprit? No, it wouldn't (since otherwise the fact it's classified itself leaks information). Maybe the investigation just yielded nothing conclusive? Which given the location and event (big explosion and lots of gas output making sure everything gets nicely distributed elsewhere) wouldn't be that surprising?
You're suggesting that when Russia cut off the gas, and Germany didn't immediately capitulate, that's evidence the leverage was worthless? It wasn't even winter yet.
Also, blowing up your pipeline just as a competitor comes on line? Whatever you think of Hersh's article, it's undeniable that Norway made a lot of money on the sabotage. Even if Russia had stayed firm and sent no gas through the pipeline, the fact that they could have alone would have kept prices lower.
Third, you're suggesting that Sweden/Denmark would have kept it secret if they found evidence of Russian meddling? They absolutely would not. In fact, if there was even evidence exculpating the US, without implicating anyone else, they would have blasted it to the heavens.
NATO-aligned think tanks have gotten better at this - something I view as a good thing, despite that I am not a fan of them, and I don't think they did it willingly. But with the rise of Bellingcat, they're now routinely publishing embarrassing material on Russia that they would have LOVED to keep secret as a bargaining chip, in earlier decades.
In fact, if there was a Russian team that blew up the pipeline, they would have left a trail a mile wide in public data and the countless leaked databases (another huge one just a few days ago, from Roskomnadzor). Bellingcat, or anyone interested, could have given you their damn cell phone numbers, if it was a Russian op. Yet they have instead remained utterly uninterested in the question of how the pipelines were sabotaged.
Russia doesn’t lose all leverage the moment they shut off the pipeline. They still have the leverage from being able to turn the pipeline back on, which impacts competitors and customers by giving the option.
Blowing up the pipeline takes that option off the table for the foreseeable future, and with the advantage that it doesn’t cause immediate dangerous supply shocks to Allies since it was already off.
Win/win for the Allies (though if public, Western Europe gov’ts would have no choice but to be pissed in public), not great for Russia who has their last leverage knocked off the table.
I personally don’t have an opinion on if the US did or did not do it, and I doubt we’d know for at least several decades.
But the US has done lots weirder stuff with far less concrete potential benefits before. hell, nearly anything the CIA had been caught doing in the 60’s or 70’s has far less plausible justification!
My personal belief is that we will never know who actually performed the acts of sabotage. But taking some Biden soundbites, mixing it with some public information and some hand-waving doesn't produce any actual evidence about who actually did it.
Did they though? Looking at the gas futures chart it's not obvious to me at all. The prices suddenly spiked much higher when NS1 was suddenly shutdown. After the explosion they actually went down slightly. They did profit, but just from the actions from the Russian side (which were earlier in time).
As for whatever you mean with competitor coming online. Towards Germany the flows from Norway didn't change that much after the invasion, Europipe II from Norway to Germany was already maxed out since January 2021 pretty much.
Second point - agreed. If for no other reason than there is little to no incentive for any of the players to share any evidence or info they may have found that would support or disprove any of the scenarios.
For Russia, if they could prove the US did it, it would strengthens the image of the US as a powerful world player with their foot on Russia's neck. If someone else did it, it would make them look even weaker.
For Western European allies, it would make it really obvious how much influence the US has on them, especially since their own fate continues to depend on the US - and it's large natural gas supplies. Even if they wanted to cut off the US, Russia is even worse for them, and they can't stand on their own two feet against either Russia or the US right now (militarily or economically). If someone other than the US did it, it would make their key infrastructure look even more fragile and vulnerable.
For the US, if they did it, it would expose the extent they are playing dirty (hurting the 'clean hands' narrative) and lose them good will with most of the public. If they found someone else doing it, it would reduce their apparent 'dirty tricks' power folks need to worry about, which is a major deterrent to enemies and allies doing dirty tricks.