Ah, but you've misread the intent. It's not that he doesn't get that it's Antonio's line from 12th Night, it's that he doesn't undestand why he's being asked why he's been duplicated. Fraser here is in the same clueless state as everyone else.

And besides, my friend, it's a crack bad!fic. I am amused that you've chosen to deconstruct it so minutely.