Read that they had to reshoot the ending because Chris Hansen has a strict "no pizza incident" rule in adapting his life to film.
PRIMETIME was supposed to have ended with Dateline's scandalous episode wherein Hansen was such a hungry guy... He wanted but a slice of that pizza...
Frank Castle in fact, would NEVER want Karen or anybody to become like him and start killing people, bad guys or not. He would kill Bullseye himself, but he would never let Karen take a life.