I'm not against Garp's characterisation
He literally didn't care about Imu's status and attacked him, something Kizaru didn't do to save his friend
Let's be honest, what happened now that Aokiji left the navy?
Did he save anyone?
No, now he's become a pirate himself and is working with the most evil people in the world and kidnapped a girl and could have caused Kobe's death
Garp chose bad between bad and worse, he had no way to defeat Imu, at least he fights pirates who break the law
Garp's characterisation is acceptable to me