If I'm not mistaken, in the Halloween event of the previous version there were people complaining that the event with the teacher felt Ntr.If this is true, this is new info. He earlier stated that the new introscene was the only ntr that was going to happen. But that explains why he removed so many posts from his blog.
The biological mother often makes comments about wanting to fix her relationship with the MC's brother as well, so maybe the author is trying to set the stage for future Ntr, which a lot of people are going to hate because things aren't set up like that in the old version of the game.
If the main character's brother is added to the game it's going to be a disaster, enough people already hated the opening scene with the stepmother.