This is a really neat project but it’s also not really a solution to anything.
First, it doesn’t solve for the scenario of person pointing a gun at you and telling you to access your top secret files for them. That will defeat most forms of security and so if physical access is a concern you probably shouldn’t be logging in at your local coffee shop.
Second, a thief who wants your computer for its monetary value isn’t interested in its contents. Your normal drive encryption and screen timeout restrictions have you covered there. They’re gonna wipe your computer, sell it, and move on.
Institutionally purchased hardware is often equipped with zero-touch provisioning (such as Apple Device Enrollment). These products can be bricked at the hardware level they moment they touch the Internet. They’ll need a new logic board, i.e. new soldered on storage, i.e. they’re not even necessarily worth stealing.
Third, the idea of a magnetic connector’s removal locking or bricking your computer seems awfully inconvenient. That’s gonna be constant false positives without a gain in security.
If you’ve got someone who is after you to obtain your secret company info and knows enough to cause mayhem, you’ve got much bigger problems than whether or not your screen is going to lock. They’re also probably going to use social engineering, targeted malware and spyware, not brute force physical access.