This fellow was a Baptist. As a Baptist, he was a Christian in the broad sense of the word. I am not saying he was saved, but for someone to say he was not a Christian does not make sense in public debate.
I think the point being made is that this fellow did not know Christ as his personal savior. He was not born again. He was not a genuine follower of Christ. But he was a Baptist, and as such he was a Christian.
It is my opinion that we need to use language in a way that most people understand it. As Christians we sometimes speak to the public as if we are speaking to one another and then we wonder why nobody seems to understand what we are saying.