Because the ingestion of human flesh and any blood is a direct offense against the Law - Had Yeshua encouraged such a thing, he would have broken the law, and His sacrifice would have been impure (and unable to save anyone), not to mention that he would be a false teacher, and false prophet.
Certainly, a different interpretation is called for.
Then you have "went back, and walked no more with him." (John 6:66...how fitting)