Your logic in this situation is impaired.
A JW might answer that the GB wouldn't teach the Trinity because it wasn't in the Bible. It would be like asking an Evangelical, "If Jesus told you to believe in Santa Claus, would you?" No! Why? Because it defies reality. And you can carry it on from there. If Santa Claus is the line one draws then where might other lines be drawn? Transubstantiation? People who aren't a member of their religion going to hell?
I know a Pentacostal who doesn't believe there's life on other worlds. She said that it would nullify Christ's atonement. How she arrives at that non sequitur is beyond me. Apparently she thinks God created the Universe to give the earth light at night. All those galaxies, each with billions of stars -- some that are completely invisible -- all made to give man something to look at in the night sky. The trillions of stars out there? Here today, gone tomorrow. It's child's play for God! No problem.
Let's say the governing board is who they think they are and Jehovah is behind them a hundred percent. Creating an "if" statement wouldn't work and shouldn't work. We should all get behind them and sustain them as God's servants. The problem is, they have no credentials. Have they spoken to God face to face, like Moses? No. Have they been chosen of Jesus as the ancient apostles were and have they been on a mount of transfiguration? No. Well, how can we tell they've been commissioned by God? Herbert W. Armstrong thought he had been called of God and he believed in many of the doctrines that JWs believe...only he wasn't on a first name basis with God. Oh, and Ellen G. White thought she was chosen of God and even had some visions of Peter and the Pearly Gates. And God told her he never changed the Sabbath from Saturday to Sunday, and she challenged scholars to show her chapter and verse where he made that change. Then there were all those Catholic children who had brunch with the Holy Mother. She wasn't interested in the Sabbath, but she had some warnings for the Popes. And so it goes. Like they say on The Sapranos, "Who ya gonna believe, eh?"
Me? I want credentials.