Melting 2" of accumulated snow from a 2m^2 area would take ~2 kWh which is roughly 1 mile of range or 0.2% of the battery, if my very approximate calculations are correct. Or, exactly 0 miles of range if you are plugged into a charger at the start of your journey.

But I think the original thread is right that you'll need to manually clean ice and snow off the windshield which, unlike the AC thing, definitely seems like a legitimate complaint against sloped windshields (though I have no personal experience on this point).