(a) Except as provided by Subsection (b), an authorized trustee may not exercise a power to distribute principal of a trust otherwise provided by Section 112.072 or 112.073 if the distribution is expressly prohibited by the terms of the governing instrument of the trust.
(b) A general prohibition of the amendment or revocation of a trust or a provision that constitutes a spendthrift clause does not preclude the exercise of a power to distribute principal of a trust under Section 112.072 or 112.073.