Someone else asked the exact same question once. It's an inane question. It's just an over-the-top generalization of what a "real" Klingon should be and do to be a "real" warrior. It's all based on one of Kor's senile drunken rants, I believe. I think "eating an enemy's heart" is as necessary to being allowed in to Sto-Vo-Kor as avoiding seafood and not wearing different fabrics at the same time are necessary for getting into Heaven.