Except as provided in Section 91-9-509, if the trust instrument provides that the trustee shall pay income or principal or both of a trust for the education or support of a beneficiary, the beneficiary's interest in income or principal or both under the trust, to the extent the income or principal or both is necessary for the education or support of the beneficiary, may not be transferred and is not subject to the enforcement of a money judgment until paid to the beneficiary. This section shall not be applied or construed to limit or otherwise diminish a restraint on transfer that is valid under Section 91-9-503.