The scientist rightly reminds us that not all the structures and functions of animals are necessarily adaptive, but can be carried along in the gene pool, purely incidental of past genetic history. He makes the point that many have come to think of the "species" as a concrete entity, without any thought as to where it comes from, or what it actually is. Yet he doesn't see the real problem, the problem of categories, the problem of reality.
Categories are an attempt to finitize that which is infinite by nature. If we concentrate on the category, and not on what it applies to, we lose an infinite amount of information - literally. Scientists are either not aware of this predicament, or simply don't care to know.