In this story, Prince Prospero is portrayed as a decadent and cruel ruler. He takes pleasure in humiliating his subjects, and at the masque (masked ball) depicted in the story, he forces them to behave like animals. At the time of the masque, a plague is ravaging the land and Prince Prospero is portrayed as being fearful of it. He thinks his castle may be a stronghold against the disease and his creation of an opulent party shows he thinks that people may be distracted from the real danger of the spread of illness. But when Prospero himself catches the disease (known as the 'red death' of the title), the implied moral or meaning is that wealth and decadence cannot eliminate the threat of death or disease, and all humans become equal when death beckons.
Appletrees, I think you are overthinking this short story, Poe does not tell how Prospero rules his kingdom. He does say that Prince Prospero takes only his friends out to the country house to enjoy themselves until the plague disappears, which means that he is selective. Ironically, the plague comes to them in ghost form and kills all of the people in the country house. Poe wants to show the reader that when death comes knocking, don't try to run; it will get you eventually. I do think you are very smart, Appletrees, only the smartest take the brain power to overthink a story, but really the answer might be hiding in plain sight.