According to virtue ethics, one should always strive to do as a "virtuous person" would do in the same situation.
If a patient wishes to continue treatment, even though the doctor deems the continued treatment to be futile, it is ethically correct, according to virtue ethics, to respect the patient's wishes, as it shows empathy and respect for the patient, which are traits of a virtuous person.
In our society, respect and empathy are connected to virtue, so if the doctor acts with virtuous properties, the doctor acts as a virtuous person making the conclusion follow the premise, thus making the argument valid.
Is this a valid argument?