I actually agree. Why the fuck are Korean idols promoting in Japan (apart from fame, money, and eventual world domination...)? Okay fine, maybe there is actually plenty reason to go to Japan (especially for zero-Korean-fans Z:ea), but at the very least, the people of Japan have the right to be indignant. If Jpop was all the rage in Korea, more than a couple people would be committing Korean seppuku (to be fair, Koreans generally have a more massive hatred towards the Japanese {partially justified}). Seriously, I'm surprised incidents like this aren't more frequent; the Japanese are actually taking it well.
But as many have pointed out, the man is a public figure, and as Benjamin Parker Jesus once said, "With great power comes great responsibility". Maybe it's not right for a man of "great power"(read: hahahahahahahaha) to be speaking his fucking opinion, but so what? At least he has the balls to be honest.
If it is of any interest, he was subsequently kicked from his label. c: