You seem to have a problem with people holding a different opinion than you about movies. Why do you take it personally? Not everyone is gonna like Rogue One. Why be a dick about it?
He's not commenting on the differentiating opinion, but at how it's expressed. (Edit: as Bobby says in his reply above.)
I'll cheerfully admit that I'm not well versed in the language of cinema, so I totally relate to people who struggle at articulating why certain things worked and don't in their film criticism. I really struggle with it (even more so when it comes to music). Everything I know I got from my community college intro to film class, 15 years ago.
I try to be careful tossing out terminology, though, specifically because I know I don't know what I'm talking about if I try to. B-grade / b-movie means something pretty specific, and it's not a bad thing, so it's reasonable that a film critic who is versed in both the language of film and film criticism would take exception to it being used to mean something it doesn't. (Though I do suggest taking your foot of the gas just a touch Bobby.