This would certainly be a good example of where NH would be justified in seeking restitution in accordance with the statute. If they don't seek restitution of some measure the precedent would gut the statute to the point no one charged with rescue costs would need to pay.

Without knowing how grandpa came to be alone during the hike, there may not be any charges to file. Did grandpa tell family to keep going and he would follow at a slower pace? Did grandpa tell family he was turning back, insisting they go on to summit and he would meet them at the trailhead? Was there a recent will change that sparked a conversation about an "unfortunate accident"? Breaking hiking etiquette is not criminal, nor is it etched in stone for everyone. Overall, this probably won't amount to criminal charges, especially if grandpa encouraged abandonment somehow and refuses to press charges.