To the bear-eared man, everyone was only a chess piece to be used by him; he didn't consider them different than normal beasts which he could kill whenever he wanted, and he didn't trust any of them. He only let his subordinates live because they were useful to him.
That was why he went personally to kidnap Aiwai and made all his powerful followers to go with him; he felt that any of his subordinates could try to cheat him and sold her to other power or steal something belonging to him while he was assaulting Aiwai. He didn't worry about weaklings, but the ten Rank 7 experts would have an easy time to betray him if he lowered his guard, a lot of powers would be glad to have a Rank 7 lackey.
He was a paranoid who never believed in others; he was hoping to learn the soul-searching skill someday to be able to spy everyone without the help of any formation.
"Will you explain that method to me? I heard that with the target's collaboration the chances of success increases."