Bruce had never imagined that after tormenting each other for four years, Schiller could still shatter his understanding of just how deranged he was. This was no longer a matter of morality or law. For the first time, Bruce felt somewhat lost.
Did Schiller want to change Bruce? Of course he did. Otherwise, he would never escape the Destiny of revolving around Batman.
If Batman refused to change at all, then Schiller might have to torment each other with him for over twenty years. Naturally, he had to take advantage of Batman still being young and make him less annoying.
Did Bruce want to change Schiller? Of course. Bruce wanted to punish every criminal, but what if one of his friends was also a criminal?
The original comics had already given an answer to that question. Batman had never given up on saving Two-Face, Harvey Dent. When Two-Face's condition worsened and he did things that broke the law, Batman felt deeply guilty, even unable to face him.
When it came to those close to him, Batman was more inclined to save them and guide them back onto the right path. That was true of Two-Face, and of Catwoman as well, rather than simply and brutally throwing them into prison like other criminals.
Batman had always wanted to change his teacher, Schiller. The reason he had not taken concrete action before was mainly because he had not graduated yet. No matter what, Batman was still a normal person with a social conscience. He could hardly beat up his teacher when he had unfinished assignments and exams he had not passed, could he?
As for gentler methods that did not involve violence, Batman had barely considered them at all. For someone whose daily work involved probing other people's minds and persuading them,