This subchapter does not limit or impair any legal right or responsibility that any person, including a physician or health or residential care provider, may have to make or implement health care decisions on behalf of a person, provided that if an attending physician or health care facility is unwilling to honor a patient’s advance directive or a treatment decision to provide life-sustaining treatment, life-sustaining treatment is required to be provided the patient, but only until a reasonable opportunity has been afforded for transfer of the patient to another physician or health care facility willing to comply with the advance directive or treatment decision.