Okay, here goes: 

  I do agree that there needs to be an objective, agreed-upon criterion for inclusion.  I also agree that square footage is not a good criterion because many colleges own a lot of land that isn't currently used for academic purposes. 

  Harvard and Tufts really are the extreme cases that warrant inclusion - Harvard has four of its eleven schools in Boston, and Tufts has four of its eight schools in Boston.  My thoughts are that a good criterion is whether there is at least one entire "school" there, being defined as a degree-granting major administrative division of the university. 

  The BU Corporate Education center isn't degree-granting .  I don't see anything about a second major campus in the Northeastern article, and anything outside the 128 wouldn't pertain to this article.  If there are any other cases of an entire degree-granding school being in another city, I'm sure someone would have brought it up already or will add it in the future. 

  I will agree that Tufts spilling over into Somerville doesn't warrant a mention, especially since it seems to be only a small portion of the campus. 

 Again, I don't think that double-barrelled locations for a few institutions will make the list unwieldy, and I do think that there's a clear enough difference between an entire school and the mentioned sattelite centers that there (hopefully) shouldn't be borderline cases.