Kawaki did nothing wrong.

He's just doing his best. If there were plenty of jonin level ninja who could stop his enemies, he'd have been glad to rely on them. Even in the original Naruto series, the villains weren't strong enough to destroy the entire village/ police force until we got into Pain. Even early series Itachi could realistically say the Leaf's Police was too much for him to handle. Put Kawaki in OG Naruto timeline, and he'll take significantly longer before he takes drastic measures. Not until maybe the Madara arc.