Trump didn't send the fleet to North Korea. He sent a carrier strike group.
As for his sending the Carl Vinson and the ships in its group, it seems to me a matter of "damned if you do and damned if you don't." The fact is Trump made a decision and we'll have live with it. It may turn out to be the right thing, or it may not.
One thing's certain, his sending the Vinson group can only be seen as "sabre rattling." Sometimes that's enough, other times its too much, and on other occasions it's altogether the wrong thing to do. AFAIK, nobody's really "sabre rattled" Kim Jong Un and the DPRK in recent times. It remains to be seen whether doing so was a good thing to do.
I suspect KJU thinks his nuclear arsenal will keep the U.S. from taking any real military action against him. I think he's mistaken. I think that the only thing stopping the U.S. from dealing more assertively with KJU is the risk of sending two of the world's major economies into a tailspin and recriminations by the PRC and the rest of the world were the U.S to unilaterally put an end to KJU's foolishness.
Frankly, I think nobody would have a thing to say about the DPRK had it not developed nuclear weapons. It could have oppressed its people and kept them living in among the worst conditions on the planet for as long as they wanted to and nobody who matters would have shed a tear.