I was going to edit my previous post when the forum timed out.
Have you played a no Illithid powers game? I think we are playing two different games - he constantly berates you for not slurping up tadpoles and chastises you when you squash the astral tadpole. It's *clearly* leading us down the garden path for transformation.
I suspect I've played more than you. I've tried both endings. I suppose you will never ally with the Emperor so I guess I can spoil this for you. At the end, he never once asks you to transform. You need an illithid in the party, so it can be him or someone else. You need to ASK for him to transform you.
EDIT: Also, the reason why he wants you to absorb the tadpole is that you are objectively more powerful with illithid powers.
And he wants us to win. That is all there is to it. His thinking that illithids are superior may rub you the wrong way, but that is not the reason why he asks you to do it.
". . . Just like you I was infected by a mind flayer parasite. Just like you I seek to be free of it . . ."
And it later tells us the truth - even if his original body was available he wouldn't return to it. He doesn't seek to be free of the parasite he seeks to "evolve" and he seeks to "evolve" us.
Yes, he seeks to be free. It's true he doesn't at that stage tell us what he seeks to be free from. Because at that stage the game has not revealed to us about the Elder Brain.
It also hides the fact that Stelmane was thrall, completely misrepresenting it's relationship with her. And it doesn't reveal the killing of Ansur until it has no other choice and indeed it advises us to avoid discovering the truth of how far it's evil has spread.
His relationship with Stelmane was problematic, I agree. He didn't want to visit Ansur because he knew it would lead to a fight, a fight which could kill us and jeopardise the mission.
It came in a false form, it misrepresented itself as the guardian and created an illusion of a sword at it's heart. In truth the sword could not kill it and the only purpose of the kabuki was to gain our trust.
I see the Guardian as a sort of Brand Ambassador, a pretty face to put to something that you would initially recoil from. It is not dissimilar to marketing.
