Re: Seriously?
Depends whether they need the security code that's supposed to be de rigeur for any write or update operations to plant their bit of code......(!)
If they do, it's: "You have physical access and the security code, that's the way it's supposed to work!".
Useful trick though. "Airbag"[1] systems are so fucking complicated these days that they are, in effect, unfixable if they go wrong (i.e. the length of diagnosis and the parts swapped to track the actual fault source down are going to cost more than the car's worth once out of warranty).
Since some utter twat made having the airbag lamp do it's "on and then off" bit at startup a mandatory MOT item a few years back, it could be incredibly helpful to have a way of convincing the ECU that the airbag system's working, even though the left-hand second redundant side-impact sensor connection is dicky or the third bouncy-castle bit on the right-hand side is two months over its planned obsolescence date.
[1] In quotes as that's a laughable oversimplification of the modern horror story.