Well, that's basically the idea of deterrence, "We have nuclear weapons, don't touch us". But the comment pointed out that the Enterprise didn't protect someone. It was just plainly used to kill. That's what weapons do. They don't "protect". A shield protects. A sword kills. Enterprise = sword. Not shield. Is it so hard to understand?
It's not hard to understand, it's just oversimplified. For instance, even in your original analogy, a sword can be used to parry just as much as to thrust, so it protects as well. Likewise, shields can be used to physically push an enemy--this was a common application of shields in formation warfare.
Doesn't change the fact that the ship was used in offensive wars against other countries, ffs. Surely you can't deny that. And that's what this is all about. This "but blabla, sword can parry, blabla"... jesus...
All I'm saying is that it isn't an indictment on the ship's entire existence, and that it served a noble purpose when it wasn't being used in those operations. Don't be petulant.