You may not have realised that the plant, though in Russian-controlled territory, had been connected to the Ukrainian grid, not the Russian-controlled one, throughout the war. The Russians' plan seems to have been to destroy its connections to the Ukrainian grid, in order to subsequently connect it to the Russian grid -- a non-trivial engineering process, especially in a war zone, and it's not clear that they will be able to achieve it.

The Ukrainian operator has apparently decided that the Russians will no longer allow them to send power home, and the repeated destruction of the power connections make the plant impossible to operate safely, so a shutdown is the least dangerous option.

None of this requires Americans to pull any strings.

_{It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II}