Heard of a similar story in the locality too!

Those de-icer cans arent great for the rubbers on wipers and seals, etc, but handy to have if in a rush.
In reality, it only takes a few mins to sit in the car waiting for the screen to clear sufficiently that the wipers can remove the rest....wait the extra 30 seconds than when you are actually tempted to turn them on, as you'll ruin the wipers passing over anything thats still frozen!