To nit 1: "totally unrelated" could reasonably mean "not in the same genus", but even relaxing that to "not in the same family" holds true for the word "cedars". The author's point about "common names" seems pretty salient

To nit 2: I fail to see what you're actually nitpicking here... How evolutionary related things are and how they evolved _are_ pretty well illustrated by taxonomic ranking. Some organisms (in a stable ecology) don't change much over time and some things do, and taxonomy gives us a good way to discuss that.