I kinda liked it when this obscure Prof. of Greek history (IIRC) at UC Berkeley dispensed with the rationale of loyalty oaths in an entirely analogous way -
A coerced oath is invalid on its face.
(Ernst Cantorowicz (sp) - a memorable name amidst the unsung)
OK Daddy, I'll kill little Billy to show how Much I Respect You (if'n ya just won't Kill Me - OK?) ummm OK? huh.. huh.. Tell Me! ya sadistic Bastard! {oops} ... {I didn't Mean That. Honest, Daddy!}
Ah.. we gets so soon old, so late smart. But always so *%^%&* Sure!