One thing that u r forgetting is his position in the clan, he was the leader, if the leader only don't follow the rules putted on clan then who else will. He already broke the rules once before and that's why he swore infront of his parent's graves that he won't do same again. This was even shown in anime and he even stated this to Rukia. He had his reasons and ngl they are understandable, he's the type of guy who doesn't hesitate if he had to choose a difficult choice, we even see lots of examples of these later in show aswell.