While a fully vanilla route might not fit the game, it'd still be nice to see the game to have multiple options. It might be ambitious, but it isn't like the story has to be completely rewritten, just different scenes and methods that get the player to a similar destination. Something like, player tries to force their way through the orcs and lose? They get a scene. Try to bribe the orcs to let you past? They get some other scene. Both methods give some player agency.
That being said, a few optional vanilla scenes building anon and sana's relationship might be good for the story. As it is, I can't understand what she thinks is appealing about him. Maybe the fact he liked her fluffy tail was more than enough for her? On the other hand, everyone seems to want to fuck her, so I bet other people liked her tail too.