See Japan loves when foreigners embrace parts of their culture, whether it's learning their language, their cultural fashion or even their entertainment in anime. Even so they keep foreigners at a healthy arms length unless on an individual level (personal friends and colleagues)

What they don't like is outsiders criticising their culture of insisting it change to suit them, and that's exactly what this post reads as "I identity as Japanese so I have the right to dictate that we change these things". I imagine they'd quickly learn what 'go fuck yourself ' in Japanese is.