Breaking down what Titus is actually saying in the trailer:

>"He is a demigod out of time"
My Primarch is out of touch.
>"Fighting for a golden age that can never dawn again"
My Primarch is deluded.
>"The primarch reborn demands the impossible"
My Primarch is off his rocker.
>"But only in death does duty end"
I have no choice but to do what he says. Only death is a release from this farce.

What happened to Titus? His face in the trailer isn't that of resolve and determination. Just dismay and wariness.