Because Sugai Yasuaki was different from the usual young masters from noble families. They thought that anyone who hit them was slapping their face; he was the opposite. He cared about reason, not people—right was right, wrong was wrong, absolutely fair and impartial.
This personality meant that anyone under him, whenever they did something, had to stand on the side of reason. His subordinates were much more disciplined than those of other powers' young masters, which in turn won Sugai Yasuaki a pretty good reputation and public image!
The flip side was, once his men had the moral high ground, Sugai Yasuaki would throw his full support behind them, even more protective than other young masters over their own people. You could say he was a pretty qualified superior.
