Thank you.
Well ... it makes sense, plausible explanation. On the other hand, it's only contrivable if we consider that what happens in Ponyville, stays in Ponyville, otherwise this "protective concealment" come to light, the enemy will get the opportunity and that will be the last day of our sweet, loved pon...okay I won't overthinking it
However, truth to say, after those villains they should have realized that there is no point to maintain the Wonderbolts. They can't handle strong enemies and let's face the facts: Protection from what? It's true that the changelings could only occupy Canterlot from inside, but neither the Royal Guards nor the Wonderbolts could do anything against them, so if the enemy can work in the castle imperceptibly the only resistance is the main 6 and most of the antigonists are intelligent, plus there is no any hostile nation which wanna conquer the ponies(yet) but your statement can strengthen the possibility of a succesful intimidation.
It's funny that they have a Royal army and a "military force", yet they pin their faith on 6 ponies every single time.