I read the article and it uses the logic of HOTD to define how races should work in LOTR. In HOTD they are telling the story of a family or dynasty and the race of the characters is important to be kept in a line which signifies blood relations.

There are some flaws with the storytelling of ROP for sure but diverse casting isn't one of them. This continued discussion on the diversity in ROP is becoming stale now and people (including the author) should move on from it.