Snowin It is indeed pathetic. However, before you nag at him, you should first look at it from another perspective. Picture in your mind an ambitious writer trying to make a name for himself. He would reply to every comment, review, and would communicate with his readers. One day, he received a negative comment. 'It's normal to receive a negative comment.' He thought. However, a time came where he only received negative comments. 'This isn't normal anymore... Is my book... really that bad?' He thought. As the negative comments increased, he slowly started to believe the comments to be true. It's a psychological effect that happens when the more you are exposed to something, the more you believe it to be true. Thereafter, he started to believe that his book is bad. It doesn't matter if someone complimented his book as he would almost always regard that compliment to be false, that someone only complimented him to cheer him up.
I don't know if that is what Tomoyuki really experienced, but I myself could relate to what he's been going through (In fact, what I wrote above was my own experience).
In conclusion: Repeated exposure to negative comments could lead to an author to think that his work that he tirelssly created day and night, is nothing but utter garbage.
Maybe... the reason why Tomoyuki is always ranting in the forums is because he thought that if he did, he might see someone that has a similar experience to him as well. This is a forum for writers, and he thought that he has much higher chances of meeting a kindred spirit if he ranted in it.
But hey, that's just theory. A film theory!
(Sorry for the long post.)