He disclaims the benefits. Yes, and this works differently than when a survivor disclaims benefits. You can name someone as a beneficiary and someone else if that first person disclaims the benefits. It's a form of contingent beneficiary. A per stirpes designation means that if a named beneficiary dies before the Insured dies, the children of the named beneficiary are entitled to the benefits, or the grandchildren of the named beneficiary if the children aren't alive, or the great-grandchildren of the named beneficiary if the grandchildren aren't alive, etc.
Designations using per stirpes designations are unacceptable.
The estate will follow the terms of the will which include the per stirpes terms. Active employees must file the form with their human resources office. If you receive benefits from the Department of Labor, Office of Workers Compensation Programs and you've been receiving these benefits for less than 12 months and you are still on the agency's rolls as an employee, you also must file the form with the human resources office. If you are on compensation and are separated from your agency or have been receiving compensation for 12 months or more, you must file the form with the Office of Personnel Management, Retirement Operations Center, Validation Section, Boyers, PA 16017. Your employing office or the Office of Personnel Management, if applicable, must receive your Designation of Beneficiary before you die for your Designation to be valid.