I don't think I quite follow you Rob - from memory the game gives you no other option. I'll have to read that dialogue again to be certain, but it does seem to me its be captured (and go against the reason principally that you're there) or fight. I'm talking about Anora's reaction in the initial Ser Cauthrien
meeting, not SC herself.
She's still an untrustworthy, smooth crooning manipulator regardless of who betrayed who.