Tell him to add oscars that are a bit more mature and he won't have a dead fish. While oscars aren't as territorial they will defend. The red devil will learn his place so long as he isn't larger. Otherwise he will have hard time keeping anything with it without a lot of aquarium space.
The cliche about adding water to make convicts to breed is 100% true. It's wild. It is the only cichlid I have witnessed breed in an aquarium. They aren't terribly territorial but will make a LARGE nest in the tank when the fries are on their way.
I suggest acclimating any cichlid to live food soon for more enjoyment of the experience. No sense owning a carnivore if they only eat artificial crap.
BTW, Choosing cichlids for your freshwater experience is a wise choice imo. Great category to choose to learn how to care for fish and get entertainment from them. I love cichlids.
ndeed