There are a whole bunch of things that I dislike about the options for the ending, but I still think that letting us recruit or save both Orpheus and the Emperor would undermine it in a way I'd also find unsatisfying.
You don't have to like it. If you personally think it undermines whatever, you can choose a different option. That's the point of having options.
Having Emperor turn on the party and literally join the enemy they have been working with you to defeat for the whole game is pretty ridiculous. Not to mention that Emperor's original form happens to be a really important person in BG lore. It's just a game, but it's still wonky, speaking as an editor.
