According to his page, https://starwars.fandom.com/wiki/Khomo_Fett
When Mandalore the Vindicated fell, Khomo's name was put forward as the obvious choice as successor. But as a seasoned warrior, he refused the position, disgusted at the thought of having to devise battle plans rather than actual fighting. Following that, he became Mandalore the Avenger's eyes and ears on the battlefield. His fierce loyalty to his people earned the new Mandalore's confidence, and he quickly became one of her most trusted leaders.[1]