"I wonder why...."
I think it’s only fair. Correct me if I'm wrong but for all the airlines around the world that offer cadet pilot programs they only take their own nationals. In Europe for cadet programs airlines only take EU nationals. In Asia Cathy only takes Hong Kong nationals, Singapore and Malaysian Airlines only takes their nationals, and same applies for Qantas, Emirates, and Qatar. So it’s only fair that MEA would only take Lebanese nationals