I'd think we'd have outgrown things like claims of "unstallibility" given prior experience with ships claimed to be "unsinkable". There's what the marketing says, and then there's reality. You will never build a technical system incapable of being coaxed into an error state. Period.

Too many years as Quality Assurance grinds into you that when engineers claim perfection, you start questioning their assumptions, and the whole house of cards comes tumbling down shortly thereafter.