WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 186, "How You Use It," now streaming on Crunchyroll.
As goofy as Katasuke is inBoruto, he does have good intentions. He only really wants to see, not just Konoha, but other nations and villages progress scientifically and it's why Boruto has warmed to the science chief. Ultimately, he knows Katasuke's work can help others, merging the mystical nature of chakra and jutsu with physics to create that better world all Hokages dreamed of, including Naruto.
However, in Episode 186, Katasuke's ambitions are dashed as his worst nightmares come true regarding what scientific tools are being used for.
Katasuke was heartbroken when the sinister Ao stole his jutsu-absorption gauntlet and used it against Team 7. It resulted in Mugino's death and, with his robotic implants from Kara and Konoha, Ao is showing Katasuke that science can still create deadly weapons. It ties back into how they were misappropriated during the Chunnin Exams, leaving the scientist feeling guilty.
Boruto fired back and defended Katasuke's work, admitting that the tools aren't dangerous -- the users are. But all this is thrown out the window when Ao unleashes Mirror Drones after his gauntlet is damaged in the fight. Konohamaru rushes in to stop Boruto from being ambushed and he gets hit by one as they rain down from the sky, forcing Team 7 to take cover.
It reminds Katasuke of when the Ten-Tails dropped larger bombs during the Kaguya War, leaving him petrified. And, while Boruto's able to destroy most using explosive scrolls, he takes a beating as well, which is something Katasuke never wanted to see. It's horrific as these drones are part Konoha's work, with Kara upgrading the rest and giving them to Ao.
It ties into what Boruto said in his angry days when he hated these tools, that they could be turned into weapons of mass destruction by rivals. Ironically, we're seeing them being used on the Konoha shinobi and as he watches Konohamaru clinging to dear life, Katasuke is repentant. Watching Mitsuki and Sarada also scrambling for their lives is changing something in the scientist, made even worse by Boruto risking his life.
Katasuke never meant to endanger the younger generation like this and he's left wondering what other work of his has been turned into evil tools. And it's not just by Kara, but by other enemies who got their hands on the research. Katasuke now realizes other folks might be making new, original weapons and so, his worst fears come true as weapons are being used for terrorism, and not to heal. It's just like the old days of war, leaving Katasuke with an existential crisis on his earnest hands.
