I think it is very well within his established peronality. He really has absolutely no time for useless and/or stupid people. Just remember his reaction to Wilfried's first half day of switching places with Rozemyne. The imcompetence and ignorance Letizia seemingly displayed was in excess of what Wilfried showed. After all Ferdinand didn't seem to have realized that Leonzio dugged and partially brainwashed Letizia. I hope he will learn of this fact and adjust his opinion accordingly.