Not sure IRS is in agreement with this statement as of 2022.
”An estate is not an individual and therefore cannot be a designated beneficiary. A 401(k) which has no designated beneficiary can only be distributed as income to the estate (code 4 on the Form 1099-R), not rolled over to an inherited IRA for the benefit of the estate”
see IRS:
https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-beneficiary
and publication of 590-B:
https://www.irs.gov/publications/p590b
don't confuse sponsored 401k plan document rules with IRS regulations
regards
