rom your question, it appears that the widow is the sole primary beneficiary, in which case any portion properly disclaimed by the widow to be passed to the contingent beneficiaries. If this is the case, the beneficiary to which you refer would be entitled to his share, unless he chooses to properly disclaim the amount. At this stage, it may be too late to take any action to prevent the beneficiary from squandering this sum. Had the issue been brought to light before the IRA owner died, the beneficiary designation could have included provisions to exclude that beneficiary, or for his share to be transferred to a spendthrift trust, if such a trust is available under the laws of the state in which you live. As you may know, a spendthrift trust is usually created to hold assets that would generally go directly to the (spendthrift) beneficiary, and is controlled by the trustee.
For further reading, see Disclaiming Inherited Plan Assets and Refusing An Inheritance.
This question was answered by Denise Appleby