Ditect R/O from 401(a) to Spouse’s inherited IRA

Continuing Saga. One of deceased client’s 401(a) plans allow a 5-year deferral for 46-year old spouse bene. It would seem if she elected that, she may be precluded from doing a direct rollover to an inhetited IRA, if they later allowed that or if a TCA or other law later allowed it. I know this is speculation, however any thoughts here?