For that matter, she's probably right. You don't send just any woolheaded bunch of novices to persuade the Dragon Reborn, and shield and kidnap him if that fails. Perhaps if Semi played ball Sarene could've put in a good word for her with Elaida and gotten her better treatment, say, summary execution rather than stilling, excruciating torture and interrogation (after all, Semi is no Tower initiate) followed by decades of painful drudgery as a slave in all but name. Then slow painful execution.