Besides showing the relative speed with which a change can ripple through a population and the incremental nature of evolution, this illustrates that once a species is better suited to its environment, the rate of evolution slows way down because it is hard to improve on a good thing. There is also the point that, if all we had from this series was one of the intermediate examples, we would have recognized it as an independent species, fully functional with nothing to indicate it was rapidly improving its adaptation to the local conditions.
Expanding this example to more typical fossil collection where a time resolution of 4,000 years would be considered an improvement, we begin to understand the situation. If the fossil you are looking at is a member of a still extant linage, you can consider it to be an intermediate fossil and there seem to be millions of examples. This leaves open the question of whether you caught a sample of a well-adapted, long-term stable form or a sample of a form in the process of improving the way it interacts with its environment. Either way, it will appear to be a fully functional, well-adapted species.
Mr. Kern appears to have been selective about what he has learned from various sources. A wider, more fully contextual selection of material might improve his understanding, if not his faith.