Yeah, Sutekh is one of those old one-shot villains who gets arguably undeserved fandom love because he was in a very atmospheric and scary story, rather than on his own merits. "Pyramids of Mars" is a very 1970s Erich von Daniken story based on the concept "the Egyptian pantheon were actually superpowered aliens", and Sutekh is what the TVTropes fandom encyclopaedia categorises as a "Generic Doomsday Villain" - homicidal Sufficiently Advanced Supervillain who wants to kill everyone in the universe just because he gets off on it. Possibly RTD may give him some more dimensionality in the second episode?