Am I missing something here that they could contradict themselves so easily?
It's worse than that - they contradict the Bible!
Genesis 50: 22-26
22 And Joseph continued to dwell in Egypt, he and the household of his father, and Joseph lived for 110 years. 23 Joseph saw the third generation of E′phra·im’s sons, also the sons of Ma′chir, Ma·nas′seh’s son. They were born upon Joseph’s knees. 24 At length Joseph said to his brothers: “I am dying, but God will without fail turn his attention to you, and he will certainly bring you up out of this land to the land about which he swore to Abraham, to Isaac, and to Jacob.” 25 So Joseph made the sons of Israel swear, saying: “God will without fail turn his attention to you. You must take my bones up out of here.”26 And Joseph died at the age of 110, and they had him embalmed, and he was put in a coffin in Egypt.
Problems to flag to JWs:
1 – Joseph lived for 110 years, much longer than people live today so not a great example.
2 – Joseph lived to see the third generation of Ephraim’s sons (Ephraim was Joseph’s son so that’s 4 generations in total!)
So their use of Joseph collapses by using the Bible.
Not great huh?