It seems to me that the few atheists who do adopt theological non-cognitivism are generally unfamiliar with the arguments of natural theology, or else they are unable to effectively refute them. I once had a debate with someone who granted the truth of every one of my arguments for God's existence, but his response was simply that the term, "God," is meaningless. He then proceeded to call the entity we agreed exists as "Shmog." Well, unfortunately for him, a rose by any other name is just as sweet.
I really do think non-cognitivism is a minority view among atheists. I should also add that I mean no disrespect to Young Earth Creationists. The reason I find the two analogous is that I often hear of atheists, such as Richard Dawkins, who refuse to debate YECs because he doesn't think their views are respectable. Might we also add theological non-cognitivism to the list of views not deserving of debate?