I think you misunderstand what the term means. For example, the control rods in some nuclear reactor designs are held up out of the core by electromagnets. Thus even in the event of complete power failure, the rods fall naturally, stopping the reaction. Since failure results in a safe state, this is referred to as a "fail-safe" system.
By contrast, if you were holding a lump of antimatter contained by an electromagnetic field, a power failure would result is the antimatter escaping confinement and annihilating with your body, releasing an unimaginably large amount of energy nearly instantly. This is what you might call a "fail-deadly" system, because a failure results in a decidedly unsafe state.
