Quality

This post is closely related to my previous post - but not quite the same.
I now want to talk on the notion of quality in artworks of all types. Quality is truly subjective. It is true "one mans trash is another mans treasure."
About a week ago now, one of the most prolific designers of aircraft addons for flight simulator posted his latest work. He has done between 50 and 75 original aircraft from the ground up, where most designers burn out after about 4. His planes are not bad, either! He is quite set in his ways. His name is Kazunori Ito, and he is Japanese.
This was posted as part of his most recent readme

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"ASS Hole. stupid, Jap !"
"Are you Insane?"

For sentences in the upper row is,
It's an answer when I cut it off to the demand of person who doesn't like my VC.
He wrote "I wants source file of your MDL file, send me it"
And, I wrote "I want to you....please make your model by yourself"

And for sentences in the the lower is,
It's a reaction when I don't bundle flight dynamic etc. to my work.

It was the first experience in my life.
I actually felt that the racial discrimination, the prejudice, and others still existed at this time.
I think.........One of the reasons why the war doesn't discontinue in the international society is here.
There are neither endurance nor a mind of the generosity.
Abuse and violence.......

I was making the models for me by myself as my hobby.
How should I respond with this?
Should I keep uploading it with the mind of the generosity?
I'm sorry for asking a trivial thing.
But, Though worlds of hobbies must be happy.................
I'm sad and frightened.

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This is because he got an angry email from some troll...
First off, why does this guy thing his version of quality is valid enough to force on the designer?
Secondly, why on earth would anyone be so madly racist?
I simply cannot understand it.
If you want to communicate with Kazunori, his email address is: KazuIto0926@aol.com
If you want to discuss this, you can do so on the blog, but also on the flight-simulator forum I frequent. Here is a direct link to the topic: http://www.sim-outhouse.com/sohforums/showthread.php?t=1600