Just off the top of my head:
- an estate probably cannot create an IRA,
- assuming this death benefit is not rollable (by the estate), then the default withholding is not 20%, but might be some other percent.
Have you checked IRS Publications 590 and 575 to see if either refers to "estate"?
BTW, the PA might be prudent to remind the estate's executor that the estate should have its own TIN, rather than use the deceased's SSN. (But the PA will follow advice from the plan's ERISA attorney rather than my advice.)