Earlier quoted context omitted.
If your attack vector is adversaries ready to deep freeze your laptop, perhaps you should do your computing in a more secure location :)
It's pretty common for law enforcement to quickly freeze RAM when busting hackers. I've definitely read of cases where suspects encryption keys were pulled from RAM using exactly this method. The killcord would have been useful for Ross Ulbricht (Silk Road) who was busted by the FBI after using his laptop in public - they grabbed it while he had it unlocked and didn't have time to put it in suspend.
That’s pretty smart by the FBI agents to wait until it was unlocked and sneak up and take it. If instead they stormed in guns drawn, all Ross had to do was close the lid and bye bye evidence.