Director Heo Jin-ho must be bewildered too

He's probably thinking, "Why are you only picking on me?"
1987, A Taxi Driver, The Attorney, 12.12: The Day, The Man Standing Next, Land of Happiness, Made in Korea, Good News, and so on...
Because his track record with films about the 4th and 5th Republics was so good, he likely had the confidence that covering the assassination of Yuk Young-soo would be a 100% success. Because he was so sure of success, he scheduled the release for the Chuseok holiday, and Yoo Hae-jin, who is known for being very picky about films, chose it. Numerous high-profile actors probably appeared as cameos without even asking for proper pay.
However, a sentiment was gradually building up in the depths of the public psyche that "filmmakers are becoming too left-leaning," and bringing up the immoral conspiracy theory that the President instigated the assassination of the First Lady acted as a trigger that caused everything to explode.