Beneficiary for the non-QPSA portion of a benefit in a defined contrib

[KJohnson]

In a D.C. plan containing QPSA/QJSA provisions a participant names his wife as the beneficiary for his entire account balance. The participant then divorces his wife, remarries, and dies several years later while still employed and without changing a beneficiary designation.

It would seem that spouse No. 2 is entitled to the QPSA benefit of 1/2 of the account balance and the prior election regarding spouse No. 1 for the entire account balance would be invalid as to the QPSA benefit. What about the other 1/2 of the account. Is the entire beneficiary election invalid so that the other half goes to his estate-- the "default" beneficiary under the Plan when their is no designated beneficiary. Or, does spouse No. 2 get the other 1/2 because the particpant was still free to name a beneficiary for the non-QPSA portion?