User blog comment:B214/Talk About What You Want! 2/@comment-24098614-20140509210930/@comment-1359322-20140510074128

Since the most basic requirement of being a Maou is being a Pure-Blooded Devil, Reincarnated Devil fail the most basic requirement which is being a Pure-Blooded Devil, so they can't really be considered qualified at all.

It's simple, imagine if a foreigner suddenly comes to your country and become its king/president/prime minster, can you just accept it nothing? It's impossible, it's exactly the same concept, no one can just simply accept a being that is originally from a different race as their leaders.