What exactly does this mean to the classicists writing in the 1800s? Lucian was a Syrian, but he born in a Roman province. What exactly was it about his writing that rubbed classicists the wrong way that would cause to to lob this accusation?
Can you give a specific example, or examples, with page numbers? Context matters.
My intuition, though, is that Lucian's being Syrian would be plenty enough for western European classicists, even more recently than the 1800s, to treat him as an outsider. 'Orientalism' -- the racist habit of treating everyone east of the Aegean as culturally Other -- is very much alive and well, unfortunately.