We can debate whether that theft was ethically permissible under those circumstances. But they still committed theft. The act itself does not magically stop being theft because we understand or sympathize with the reason behind it.

What? By that definition nothing is theft unless ruled such by a court. Which funnily also means that if someone takes anything but doesn’t get caught, they haven’t committed theft?
Ergo any corporation powerful enough cannot commit any crimes, due to not being sentenced.

That’s bullshit and you know it.
This isn’t about if the guys stealing the copper committed a crime or not. Obviously they removed property without consent, which is theft.
However, is there such thing as “good” crime? Yes. Same as the mother stealing formula for her baby, or the homeless person stealing bread, or these guys stealing copper from AI data centres.