Oh, I 100% agree. It was a _terrible_ narrative choice by the dev, and I agree that it fails for all of the reasons you mention.Just got home from work and have to get prepared for something else, but I wanted to pop in with a short message. Raife, Jufot, I just say I'm generally unimpressed by the "male MC seduces a (previously) lesbian couple (and then the entire relationship comes to depend on the MC)" trope, even if it is explained as a realisation that they are bi. I can elaborate on this later, but I tolerate less inconsistency of character with NPCs than with MCs who are guided by player choices. Beside that its only purpose is to stroke the ego of a subset of male players.
I also could not agree more strongly that inconsistency of character -- characters who are _not_ true to themselves, particularly for porny reasons (e.g. to flatter the ego of male players) -- destroys the credibility of narratives. This is exactly why I generally hate 'harem' games, for example: creation of a harem generally forces the LIs to deviate from their personalities for reasons that are not credible.
As I said, I played through this scene and hated it so much that I stopped playing the game in disgust... and only picked it up again perhaps a year later. There are definitely some faceplants in BAD, and that scene was the worst of them.
I strongly suspect that jufot feels the same way, and that we both rather deliberately chose to reinterpret the scene (do a mental rewrite) in our own minds to avoid just dumping the game entirely.