I was thinking of what Danzou said and it definitely seems once again has the best intentions for the village. When he said he should have killed that traitor hyuga sooner , its because when a hyuga dies the eye ability is sealed , as confirmed here
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and in episode 63 while nejis in the hospital . So what i think is for someone to get a byakugan must be done while a hyuga ninja is alive.
Ao did say his eye was a souvenir so this probably means a reward right before the hyuga he battle passed away