I never heard the man before this article. So here is my perspective.
Many people who write books on societal issues have a strong opinion. I would include myself in that matter. Whatever you said about John could also apply to me. If my book gets popular, I could see similar articles being written about my work. Expecting opposition is part of putting ideas out there.
My take on theologians and amatuer theologians is that many of them believe their interpretation is correct; and differing interpretations are wrong. John is no different. But he just might have something interesting to say. The Bible is an interesting book in that different interpretations are possible.
John and his interpretations have gained some degree of popularity. But this won't be the first time. Trying to stop or discourage interpretations we don't like has been, historically speaking, kind of pointless.
Will I read John's book or blog? Probably not; my reading list is long. There are all sorts of Christian pastors out there peddling their own interpretations of the Bible.
But it seems that John has stepped away from the standard version of Christianity. He just might be making people think differently. That might be a good thing.