No matter involving any vendor or contractor, in their individual or any other capacity, shall be considered during a closed session on any transaction involving the system unless, prior to the closed session, a written disclosure has been submitted by the vendor or contractor of any campaign contributions aggregating two hundred fifty dollars ($250) or more and any gifts aggregating fifty dollars ($50) or more in value that the vendor or contractor has made during the preceding calendar year to any member of the board or any officer or employee of the system. Failure to disclose the campaign contributions and gifts shall provide the basis for disqualification of the contractor or the vendor.