Dai Bao was already acknowledged as the next Patriarch after his father, Dai Feng.
And so there was greater pressure for him to collect achievements, proving he is worthy of his future role and not just because he is the eldest grandson and the only son of the current Patriarch.
While Dai Chen was already convinced that Dai Bao was in the right direction to being ready for his future role, the elders weren't of the same mind.
They have seen him with the majestic Hippogriff, yes, but there were still doubts by some. With the opinions being so divided, the organizers decided to be cautious and only matched Dai Bao with a beast that is of lower rank than the one he applied for.
It was better to test him out if he could manage it first.
Still, the beast that they have assigned was not really considered low-ranked for others.
It was enough to showcase the future Patriarch's abilities with minimal risk of getting humiliated.