Lucas Sinclair was strong enough to disregard the orders from the court. Heck, his family had enough power to stop the case file entering the judicial system. it was not just Sinclair family, many families, the main branches at least, had such immense power. Lucas respected law, that's why he did not go against it. Not because he fear it or the punishments.
It was not the case in regards to Miss Sophia. Whichever name she used, she was not strong enough to go against the law. Even something so arbitrary and archaic as Family Law. Though Lucas would love to help her, he knew from experience that she would not accept it. He still remembered their talk when she refused his help. It happened few weeks back. Back at the time when he was not so fascinated with her or thinking of her.