Hou Niao had no reason to refuse, because this involved the pride of the grassland people; they had survived thousands of years of strife in the Cultivation World through such wild methods, which also embodied great wisdom.
It's the wisdom of how to control the level of conflict.
What would happen if he went? A one-sided massacre, and then what? Both sides would double down, could the grassland people afford to?
So it shouldn't be a one-sided slaughter but a fairly matched brawl, gaining some benefits in the process, without provoking the opponent's sensitive nerves, and thus wouldn't escalate to a power-level confrontation.
This is a method the grassland people have tested and proved effective over a thousand times, leaving behind a reputation on the Continent as rebellious and disobedient, yet they still survived until now.
So, it would be inappropriate for him to go, as it would disrupt this balance.
