What was the point of blocking the robot outbreak using Kill-Ballad?
I believe the game was a defense against fixing the problem. 

The guy who started it was one of the people who worked on the game with Frau, so he must have been betting that the person who was trying to gain access would not beat the hacked kill-ballad character, even if it was Frau herself. 

(since she made the system she could give herself the rights back to fix the problem but couldn't play kill-ballad well enough to beat the hack)

(It also gave Kaito a chance to save the day ;])