I don't think that we are far enough along with this investigation to simply castigate the pilots for this.
Yes, on the surface it does appear they shutdown the wrong engine
but for what reason ??
Why shut anything down to the point where it has to be restarted? Why not just cycle something for a few seconds to confirm that it's still working?
I await the teardown of both engines and a full analysis of their performance capabilities before judging the pilots actions.