In the anime it didn't clear up Remington's reason for sneaking a demon in the training room and that made me suspect he was evil. But from here it was very clear. He had set up a battle that Rosette couldn't win through firing a gun, it was clear she was going to leave one way or another, so he wanted to prepare her for how dangerous things will truly be with a purely mental battle. On top of that he was ready to save her as soon as things went wrong. This both explains why he sent a mind eater in the maze and why he didn't tell her. If she was ready the test wouldn't be the same test after all.
