I think that since he can't transform, they probably merged the two, so to speak.
Make Irumean an aspect of his personality.
Though he's more arch and... sleazy? Not in an "inappropriate" way, so to speak. But like, well, a mob boss.
He stayed calm while Mafiazz poured burning oil onto his own eye, at his behest, and put the blood onto his own hands.
I don't think we would like this boy to "turn evil". I think an evil version would just sign up with Kiriwo. Just get married to consolidate power. Do all the heinous crimes.
Then one day put down the glass pipe (only thing I can think of that will straight up turn you evil irl) and look in horror at what he did to attain whatever equivalent to Royal One exists.
I mean not literally "evil cycle" for Iruma, but more like design style and perhaps different aspects of his personality.
Look at Clara and Ameri of this manga. Compared to their original versions, they are in scenarios of "Oh no! They are hot!". In this version, Clara is more seduction cute, while Ameri has sexy handsomely.
So, it's likely author will bring similar aspects as "disguised as female for undercover" for Iruma in this manga, since there are a lot of DNA sharing between this manga and the main manga.
I got feeling that when we got future chapters on "Female Irumean" in this manga, I suspected Iruma will be in the extreme range of "Oh No! He/She is hot and scary!" than usually. That's what I mean about "too much for mere mortals (readers)".
....would Iruma be more hot goth with vibe of "Madame" when in his undercover as disguised female? This could be possibility for balance between Ameri, Clara, and Iruma (disguised). I can imagine there will be "explosively" reactions from the fans of both mangas.