Beags,
Point taken, but if the firing path is 'mechanically interrupted' as a safety means, there must always be a concern that despite setting the arming mechanism to the correct 'live' position the interrupt remains fully or partially in-place. This situation may or may not deliver a tactile feedback to the operator to warn of the problem. As we are all routinely reminded, the impossible occurs.
Hence, there is a design issue to be considered in terms of minimising any risk that the seat would not fire when needed and MB has opted to keep the primary firing path for their seats open at all times.
lm