I don't understand the problem. The driver asks for oral sex, and the girl stabs him in the femoral artery.
This is an ill-advised action if you have just committed justifiable manslaughter against an attempted rapist, and it wouldn't facilitate an easy ride with the Police. (The Moscow Militia are difficult enough to get along with at the best of times from what I've heard). Its possible that the Russians may have to take the case to trial after this kind of initial disclosure and if there were no witnesses to the stabbing itself.
This article is easy to misconstrue. It says that she was 'charged with murder committed in the state of temporarily insanity', but that the sentence is to be passed today. If they have reached the sentencing phase of the trial then it ought to say that she was found guilty not just 'charged'. Anyway, I hope she doesn't get a custodial sentence because Russian prisons are bloody terrible.