Supplemental disability benefits payable to a participating employee who fails to cooperate with a rehabilitation program prescribed for the employee shall be decreased by fifty percent of the amounts otherwise payable to such employee. In determining the amount of any reduction in benefits under this section, the participating employee shall be presumed to continue to receive benefits payable under the Act. Failure to comply with a vocational rehabilitation assessment process at any time the employee is receiving supplemental disability benefits may constitute a failure to cooperate for purposes of this section.