twin city having two meanings indeed makes the clue not be incorrect. But is it the most common/used meaning? (That is usually the way on jetpunk isnt it, if there is some less known alternative option, go for the more known ;) )
I have only heard of twin cities as two cities from different places in the world, that form a partnership, to form friendships, exchange culture, support eachother etc. (practically all of our cities has a twin city)
Never heard of the other term, which indeed after looking it up is not wrong, but I doubt if it is the more know term. I can't say for certain obviously, I havent interviewed the entire planet ;) But my bet would be on the other term. (but maybe in america the other one is more known, since twin cities are more popular in europe)
Plus he was right. So it is kind of weird to strongly disagree with him. That doesnt mean the answer given is wrong. It is just two meaning of the term twin cities.
(it feels like saying I strongly disagree that finland borders sweden, because norway borders sweden and all norwegians will agree with me. just because one way is right doesnt make the other wrong)
Either way this way phrasing makes it unclear what is meant with the term. (I personally would never in a million years would have thought of an agglomeration.)
As democracy is perfected, the [Presidency] represents, more and more closely, the inner soul of the people. We move toward a lofty ideal. On some great and glorious day the plain folks of the land will reach their heart's desire at last, and the White House will be adorned by a downright moron.
- H. L. Mencken"
this example from Marlene Mountain:.............
...........................the program refuses to do it in 3 lines, you get the picture, i hope