mmm...
Les read the verses subsequent to the one you cite (even though Rood, not a Jew, can’t be a “brother”):
20. But the prophet who intentionally speaks a word in My name, which I did not command him to speak, or who speaks in the name of other gods, that prophet shall die.
21. Now if you say to yourself, “How will we know the word that the Lord did not speak?”
22. If the prophet speaks in the name of the Lord, and the thing does not occur and does not come about, that is the thing the Lord did not speak. The prophet has spoken it wantonly; you shall not be afraid of him.
And what else do we know about what should happen to false prophets, hmm?
Matthew 12:38-40 (NIV)
38 Then some of the Pharisees and teachers of the law said to him, “Teacher, we want to see a sign from you.” 39 He answered, “A wicked and adulterous generation asks for a sign! But none will be given it except the sign of the prophet Jonah. 40 For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth.
Would not it be impossible to fulfill this prophecy and indeed many others without his sacrifice? To which your theory that his physical death indicates he was a false prophet can not logically be applied.