Despite not wanting to change anything, Tyson got James Cameron to go back and alter the night sky in Titanic to make it accurate to the day it sank. That's pretty impressive.
Just the fact that the man is the primary reason Pluto isn't a planet anymore, and yet is considered "The Coolest Scientist in America" is pretty darn impressive, considering the sizable backlash that decision created when it happened.
The story about the kid who asked him "What would happen if a black hole struck another black hole" continues. The boy in question is about to graduate high school with a 4.0 average and a full-boat scholarship waiting for him at MIT, all on Tyson's dime. More than anything else, that is why he's the coolest scientist in America!