I didn't see it that way. Trevor was nobody, he was a vessel of the mandarin. The Mandarin in the MCU happens to be american, no beard. He still had the same motives. It was more like an origin movie FOR the mandarin, as much as a close to stark's arc. Killian, this man, creates this mandarin persona, to hide himself behind, to take the brunt of what he is doing. but in a desperate time, he accepts who he is, and says, you know what? I created the persona, the mandarin, everything he's supposedly doing, I AM doing. I AM the mandarin.
The fact is that the movie advertises ben kingsley's character who physically resembled the mandarin, and built people up. The twist not only through people off guard, but it just seemed so...stupid, if the character was physically there. But I get it, and I enjoyed the twist, but i get why people don't.
my problem with the movie has nothing to do with the twist whatsoever.
add the "mandarin" aspect of Killian's character onto kingsly's character...and leave kingley's character a nameless mystery.
there's the mandarin he wanted, no need to be condescending, you're better than that