I am wide open to hearing it's a bad idea, but I'd rather hear why
it's a bad idea. All I can think of is the concern of lighting yourself on fire, but I'm not sure that's valid or not, with a flame you can point away from yourself, and being surrounded by snow moreover. But I'll gladly hear if I'm wrong.
EDIT: I guess the flame might steal your air also.
1. just plain stupid to ride with a blowtorch in your pocket. one big enough to make any kind of impact of melting enough of that snow would need at least a 10oz canister and something that big would have to go in a backpack and you'd never be able to get to it.
2. flame from a blowtorch requires oxygen. using up your available oxygen by trying to melt your way out is retarded. and yes, burning a propane flame generates carbon dioxide.
3. you could set yourself on fire, or at very least burn yourself/melt synthetic clothing onto yourself
4. blowtorches require external spark to light them, either from an open flame, electric piezo device, or a flint striker. good luck firing any of those up when you're packed in snow.
5. not sure about propane, but liquid isobutane stoves do not function well or sometimes at all at elevation, and in subzero temperatures.
6. it would take forever to make any significant progress when all the while you could have been digging yourself out or releasing your bindings (assuming you have enough mobility to extract and use a blowtorch)
its a fucking stupid idea