Science Fiction is an incredibly broad genre.
"From Earth to the Moon" by Jules Verne is something i'd consider Science Fiction. It has barely any social commentary and doesn't play in the future. It's still science fiction in the strictest meaning of the words, an adventure novel based on a technological premise.
"A Clockwork Orange" plays in the future, and boy, everything that plays in the future is science fiction, right? Well, future should bring scientific/technological evolvements, so fictional science is bound to be part of it, so - it's science fiction, isn't it? Either way, that book has a whole lot of social commentary.
An then there's stuff like "Star Wars". A long time ago, in a far far away galaxy. So, no future, no social stuff, but IN SPACE! And space, again, implies (fictional) technology/science, so hey, those definitions seem to get along after all. I assume that Star Wars is closest to what a certain "Nutty Nuts" person from that blog post might like, because it spends no thought on how human society might evolve (as it's neither about humans nor the future), and is basically an adventure tale with lasers and space ships. That's one of the reasons why i can understand people considering Star Wars "not exactly Sci-Fi", though obviously it fits the definition i gave.
It all comes down to what you expect from Sci-Fi. And whether you think a story about Cowboys in space can be any good.