No I think it's an interesting debate
But, what's the debate? If a couple of filmmakers "fathers of Modern Science fiction"? What does that even mean in this context? And the answer is ... no.
Mostly because in order to be a father or mother of an artistic movement, one has to have influenced others... Have either of those two in their very limited way influenced anyone?
As far as movies go, we're still living in the fucking shadow of Blade Runner's production design.
And a movie and TV show... talk about tunnel vision... that ignores all the work in books and comics and other media.
So. The debate is sorta of ludicrous and perfect for social media all at the same time.
You yourself consider the last Jedi to be the greatest star wars movie of all time do you not?
So, therefore you must rate Rian Johnson incredibly highly amongst masters of the science fiction. Superior to George Lucas by default, yes?
Because he wrote and directed a good to great movie, he's suddenly a master of science fiction? I guess if you say so, because no one else really is.
George is a great idea man and producer, but, the movies he directed are the weakest. But, certainly Star Wars as a whole influenced Science Fiction, so, yeah, he'd still be a master... Just not a very good director.