(a) It is a ground for removal from office if the commissioner:
(1) does not have at the time of appointment the qualifications required by Section 31.023;
(2) does not maintain during service as commissioner the qualifications required by Section 31.023;
(3) violates a prohibition established by Section 33.001, 33.003, 33.004, or 33.005; or
(4) cannot, because of illness or disability, discharge the commissioner's duties for a substantial part of the commissioner's term.
(b) The validity of an action of the commissioner or the department is not affected by the fact that it is taken when a ground for removal of the commissioner exists.