WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 195, "A Vase," now streaming on Crunchyroll.
In the Boruto anime, Shikamaru hasn't been too keen on Naruto's plan to adopt and babysit Kawaki at his home in Konoha. While the leaders of the other villages eventually agreed to it, Naruto's advisor was adamant that Kawaki was a weapon who could sneak off on his own any time, and given how he went off unchecked at the Ryutan lab, cause massive damage.
Not only does Kawaki still not understand his own capabilities, but he is also someone they can't trust as they don't even know if he's a Kara infiltrator or not. Naruto ultimately decided that imprisoning and keeping watch over him was too cold. But, as Episode 195 proves, Shikamaru may have been right about keeping Kawaki on a tighter leash.
Being a teenager, Kawaki's fuse is short; his temperament leaving a lot to be desired in Naruto's home. He's lashed out at the dinner table, broken Himawari's vase and riled up Boruto to the point they almost come to blows. In the latest episode, things only get worse when Naruto shows him around town as the pair search for a replacement vase. While out and about, a kid bumps into Kawaki while running away from a friend. In the blink of an eye, Kawaki's arm turns into its giant monstrous form and grabs the child, ready to crush him.
Luckily, Naruto blocks it and frees the kid. He's upset because he expected Kawaki to be more composed, knowing the risk out in the open, and interprets the move as the kid being ungrateful about the degree of freedom he's been offered.
The problem seems to be that his body is operating on pure reflex. Sure, Kawaki tells the boy to be careful when running (in a condescending manner), but just like when he almost killed an animal abuser in Ryutan, his body -- a scientific ninja tool created by Kara -- seems thirsty for violence and is influencing his instincts -- not the other way around.
Shikamaru thinks this is what differentiated Naruto and Sasuke when they were honing their gifts at that age. Naruto was a bit more in control of Kurama's abilities (which were sealed), and Sasuke knew how far to push his Uchiha powers. But Kawaki doesn't know what or who he is, which is why Shikamaru was adamant that the Hokage taking him home was a liability.
Additionally, had Kawaki killed the child in the highly crowded streets, it'd be a PR mess. The media would be all over it, other nations would get spooked and Konoha's credibility, as well as Naruto's as a leader, would be shot to hell. There's no amount of damage control that could be spun by Shikamaru, who once more shows that as cruel as he can be, his philosophy of proactivity can be smart.