I'm not sure if you're serious but if you are, this is dumb advice.
Change happens from within. Change happens locally.
If he enjoys the Church and its teachings, but has a problem with a few things of the many good, then by staying he can help promote change.
It's advice like yours, "if you don't like it then leave" that allows bigotry and hate to prosper.
It's people coming together and sharing ideas, much like how Joseph, the quorum of the 12 and early members did, that allows the church to grow, evolve and become stronger.
Remember, the prophet is not infallible. They are wrong a lot. If we all left the church every time a prophet was wrong, there would be no church.
And for those of you that are uneasy about the gay children policy, stay strong with your uneasiness. It people like you that eventually led to changes in who receives the priesthood.
Right now there is some teenager walking around without that hate inside him, and that teenager will eventually become the prophet, and much like President Kimball, will wonder why such stupid, hateful ideas have a place in the church. And when that happens, policy will change and the church will release statements throwing the current regime under the bus, just like how the church did that to Brigham Young recently.
Nothing good comes from just walking away.