The commenter you're replying to would be better off giving his money to a company that puts privacy (and FOSS) above all else, instead of trying to bribe a lost cause (let's not forget about the 3 times Lenovo has been caught with nasty factory-installed malware on their consumer laptops).
Here's the Librem laptop homepage: https://puri.sm/products/
Personally, I am not worried about quite sophisticated attackers. When securing my house I'm worried about run-of-the-mill burglars, and this is like that.
AFAIK the airbag accelerometers are designed to detect much larger accelerations than e.g. the ones in a smartphone, and are thus essentially completely insensitive to anything lesser than a huge impact -- spurious airbag inflation is one of the things the manufacturers really, really don't want to happen.
Many of them are just mechanical switches actuated by a weight, with no active electronics (makes sense for such a safety device to be as simple as possible): https://www.youtube.com/watch?v=mWSlwhYyOhI
And even when not impacting anything, a car is not exactly a quiet and vibration-free environment either...
On the other hand, with an external webcam, I can simply disconnect it. If you have a laptop built into a laptop that is not so easy to do. At least, you have to trust the laptop's manufacturer to do that, while a builtin plastic cover is so simple one does need to "trust" it; at the same time, you can't retrofit it on a laptop... :(