Hal didn't like the direction the film took the Romulans, but he tried to dress up his opinion, and his own notions about Trek's universe, as fact.
Maybe less a notion, as a product of observation over time (fictional centuries) of a pattern of past behavior.
So becuase MILITARY Romulans (and only the ones we've seen at that) act a certain way all Romulans even CIVILIAN ones have to act in that same manner?
But why would a military Romulan, a cilivian Romulan and a government Romulan (we've seen all three) possess different cultural norms? Cultural norms are ingrained into the societal whole, it likely that Romulan don't even recognize that they are as a group duplicitous, it's who they are. Captain Mike is simply pointing out a in common characteristic that Romulans have constantly displayed.