Yeah I mean he deserves to be on the list and maybe Spielberg doesn't deserve to be #1 but I'm sure there's better choices than Scott. And I say this as someone who ranks Alien as a top 3 movie of all time.Still deserves to be at least #2. Alien and Blade Runner are Sci-Fi classics, and he has made a Sci-Fi film more recently than Spielberg.
Maybe it's just residual salt from Prometheus.
And also Nolan is weirder the more I think about it. Memento and the Prestige are great but aren't even sci-fi iirc. Batman Begins and the Dark Knight are great comic book movies but not sci-fi, Interstellar and Inception are really the only sci-fi movies he's done and both are among his weaker efforts imo.