Sure! It would work!
I would still probably pick dedicated seatbelt cutter or similar.
Getting access to rescue cutter should be as easy as possible (one handed or without hands). If you hang on your seatbelt with broken arm, it would be nice to be able to use the tool even with your teeth.
Leatherman:
Charge TTi, AL, Squirt PS4, Surge, Juice XE6, CS4, S2, ST300, Crunch, OHT, MUT, Rebar, Brewzer, Signal, Raptor, Tool Adapter, Croc, Wave, Style CS, Freestyle, Skeletool RX, Micra, Wingman
SOG:
PPP, PowerLock, SwitchPlier 2.0, Paratool, PowerAssist, Reactor, CrossCut, PowerPlay
Gerber:
FliK, MP600 ProScout, MP600 blunt, Dime, MP-1, Diesel, MP400
Bahco:
MTT151, MTT051, MTT121
Knives:
Spyderco PM2, Tatanka, Bug, ZT 0452CF, CS Recon1XL, Benchmade 940-1 and 482
SAKs:
Too many to list here...