Russia had stopped gas flows on NordStream 1 26 days prior to the explosion [1].
This was after a series of reductions, stops, and restarts where they reduced flows and tried to get Germany to break sanctions to send parts. That they then ultimately rejected and wouldn't receive. E.g. [2].
When Germany offered the parts. They refused them, stopped NS1 entirely and offered to activate NS2 with Germany. [3] Germany refused and resisted the blackmail attempt.
Then the explosion happened a couple of weeks later. After that Russia again offered to activate NS2 with Germany. [4]
In this context, the US going ahead with the plan to demolish NS1, and leave NS2 50% operation makes zero sense.