I think there are 2 things here
1. Newton didn't lie. I think everyone agrees that if you are doing 60 kias with a 60 knot headwind and that INSTANTLY changes to a 60 knot tailwind, by either turning the wind or turning the aircraft then you have a little problem. Thats the theoretical application.
2. The practical application during most flight is that if the aircraft is flown properly during the turn then it will have time to overcome its inertia during the turn.
You can't argue with Newton but with airmanship you can out manouver him. I think you guys are aguing two sides of the same coin.