Sure, right now. When the winter comes and heating bills skyrocket, there will be those in Germany who want to turn the gas back on. Or... would have been. That option is gone now, at least for this winter. That's what the US might have gotten out of it.
> It would be a tremendous risk to be discovered
The US has taken more severe risks before, such as tapping the undersea cables in the territorial waters of their nuclear armed adversary during the Cold War, in principle risking global nuclear annihilation. The primary rule clandestine submarine operations play by is "don't get caught". If the US did it and did it properly, nothing will ever be conclusively pinned on America.
> Denmark could trigger Article 5 against the United States.
Fantasy scenario, get real.
As said before, it would be to prevent Germany from caving and turning the taps back on in winter when they are desperate for gas.
Another option is that somebody wanted to plant explosive devices for future use, and something went wrong. Hard to see how both pipelines would blow up then, but maybe a possibility.
Whoever did it picked pretty much the perfect time from the perspective of deniability.
This isn't really a counterpoint, since it's all the same risk for every potential suspect.
Its not what I want but an attempt at an unbiased assessment.