I see that you have gone back to claiming an interchangeability in meaning that is not supported either by dictionaries or general usage.

The 'fuzziness' is just a consequence of your (and the article's, and some comments, but by no means everybody's) idiosyncratic usage: by treating 'Byzantine empire' and 'Byzantine civilization' as if they were interchangeable terms, then you have to explain that civilization on the Bosporus did not end with the fall of Constantinople, as you did a couple of posts ago. If, however, you stick with the usage that is preferred by a ratio of 50:1, then the fuzziness and potential confusion goes away, as then you would be using two distinct terms for two distinct concepts.

Your last paragraph is a non-sequitur, as the issue is not whether 'civilization' just means urbanism here, but whether it means the same thing as 'empire'.