I think if you keep your vehicle well maintained you have little to worry about. In the event of a front end collision... Keep a fire extinguisher handy in your car if you're worried about it
Edit: I think I have little to worry about because my evaporator is located in the rear of my engine bay and I am planning on buying a heavy duty front bumper. As far as that isolated incident goes... I suppose if your AC hoses run near any fans then this idea poses a few risks.