Considering an overwhelming majority of modern science fiction (or at least modern American science fiction) draws from Firefly or nu BSG, then I'd say Joss Whedon or Ron Moore have more of a claim to being the "fathers of modern science fiction." Aside from being the current head honcho of Star Trek, what has Kurtzman contributed to science fiction? And I'm not even sure how Rian Johnson qualifies as a father of science fiction. I'm not saying that to diss the guy, in fact I quite enjoyed TLJ. But one Star Wars movie is not enough to have under your belt to be a father of science fiction. And Looper certainly didn't have enough of an impact to bestow the title on Johnson. I think that's it as far as his contributions to sci-fi go.