The author has lived in Japan and studied Japanese for a long time. If you read some of his other posts for context you will see that he deeply admires and loves the Japanese people and their culture.
This article appears to me to be a cathartic rant about Japanese being so difficult to learn that even many Japanese don't master their own language. I lived in Japan for about 3 years and I can corroborate that Japanese people struggle with their own language. For example, the development of word processing has made the problem even worse. When Japanese people consistently use computers for writing they call themselves "Wa-pu-ro baka" (translation "word processing idiot") because they quickly forget how to write kanji by hand.
Actually it is two rants in one. The first rant is about how college level educational standards are very different in the U.S. and Japan. Although I never attended university in Japan, I've met many Japanese college students and their stories corroborate the author's claims of ridiculously easy grading standards.