A witness may not be any of the following:
(1) A person designated to make health care decisions on the principal's behalf;
(2) A health care provider or professional person directly involved with the provision of care to the principal at the time the directive is executed;
(3) An owner, operator, employee, or relative of an owner or operator of a health care facility or long-term care facility in which the principal is a patient or resident;
(4) A person who is related by blood, marriage, or adoption to the person or with whom the principal has a dating relationship, as defined in RCW
7.105.010;
(5) A person who is declared to be an incapacitated person; or
(6) A person who would benefit financially if the principal making the directive undergoes mental health treatment.