Prof. Radaelli: Was wall-builder Pope Leo IV a bad Christian?

We were asked by a colleague of Dr. Enrico Maria Radaelli, disciple and guardian of the legacy of the late Romano Amerio, to post the following brief reflection/question on the matter of border walls and Popes:

"Regarding Walls and Popes, it would indeed be most interesting to know what Pope Bergoglio thinks of the famous Leonine Walls, erected by his predecessor Pope St. Leo IV in 847 to defend Rome and the Pope’s residence from the Saracens, the Muslims of that time. Was Pope Leo, sainted and responsible of many a miracle during his lifetime, not 'a good Christian?'"