i thought about how byakuya & his suppression of rukia's potential walked hand in hand with rigorous training to his standards —— especially post the first soul society invasion by the karakura gang. his initial treatment of rukia was pure dismissal. after her adoption into the kuchiki clan, byakuya had not properly looked at rukia even once. at the same time, he was overbearing —— a protective nature, but one crafted out of sheer selfishness that was meant to see his promise to hisana kept. at her acceptance into the gotei 13, rukia was not given a seated position. for anyone who knew the inner workings of the noble clans, it was clear as day that this was the doing of byakuya.
unbeknownst to rukia, byakuya made certain to impose teachings upon her that he knew would suit her skills well. at the time of the soul society arc, most of these teachings were given by tutors that withstood the selection criteria of byakuya. post soul society & prior to the arrancar arc, byakuya taught rukia personally in matters of kidō. a reflection of this was seen when she fought aaroniero arruruerie & used bakudō #61, rikujōkōrō. aaroniero made the claim that byakuya specialized in rikujōkōrō. while aaroniero was initially an unreliable narrator before the battle, the arrancar was correct to presume so —— especially since rukia's reaction confirmed it.
so, while byakuya was able to halt rukia's growth within the ranks of the gotei 13, he did not do so for everything. byakuya recognized the unwavering loyalty that rukia held for her friends, especially when it concerned the shinigami daikō. but above all, he recognized that it was part of her sworn duty to do so. in the eyes of byakuya, shirking one's duty was neither a choice nor an option. now, if that included going rogue & disobeying direct orders to retrieve a certain someone from hueco mundo, it would earn his silent seal of approval.