It’s an interesting line of reasoning. And if a person seeking to get a disclaimer recognized were my client, I might consider using that reasoning with other arguments.
The minimum-distribution rule includes: “Accordingly, if a person disclaims entitlement to the employee’s benefit, pursuant to a disclaimer that satisfies section 2518 by that September 30 thereby allowing other beneficiaries to receive the benefit in lieu of that person, the disclaiming person is not taken into account in determining the employee’s designated beneficiary.” 26 C.F.R. § 1.401(a)(9)-4/Q&A-4(a) (emphasis added).
The rule recognizes the possibility that a plan’s administrator might recognize a disclaimer.
But there is no Federal statute (and no rule or regulation interpreting a Federal statute) that requires (whether as an ERISA command, or as a condition of IRC § 401(a) tax treatment) a plan to recognize a disclaimer.
(For a governmental plan or a church plan, if not ERISA-governed, one would consider applicable and relevant State laws.)
If a plan’s administrator plausibly interpreted the plan to not require recognizing a disclaimer, I doubt a contingent beneficiary’s claim for a benefit, or action for equitable relief on a fiduciary’s breach, would succeed. Many plans’ documents grant the administrator powers to interpret the plan. At least since February 21, 1989, courts defer to a fiduciary’s exercise of that discretion unless an ostensible interpretation is so obviously unreasoned that it is an abuse of discretion.
(The result might be different in an interpleader action. Courts sometimes interpret ERISA by filling a perceived gap with Federal common law.)
All that observed, I imagine many practitioners would interpret a plan that does not expressly preclude a disclaimer to allow a qualified disclaimer.
Such an interpretation would be logically consistent with a common-law idea that a person ought not to be compelled to accept a gift.