My brother, an MIT graduate, ran for the city council of Cambridge, MA, among other things criticizing a comment by another candidate that the local college students shouldn't vote because they were only there for a short period of time. On some level this felt fallacious to me, insofar as the college students represent a particular set of interests; if there are 20,000 students at any given time, the 20,000 students who are there might be expected to represent the 20,000 students who will be there in 10 years, and the short time that any one student is there is (exactly) balanced by the large number of different students rotating through.
On the other hand, increasingly as government gets more local, I can think of a compelling case for restricting the franchise to people who have been there a while. In particular, I think we should do so where Tiebout sorting might be expected to operate well — where people have reasonable choice among and information about different communities in which to live — and where the near term is to be traded against the long term in a significant way. Where there are decisions to be made with long-term ramifications — should we raise taxes to build more classroom space? — allowing people to move in, vote for the short-term expedient, and move out before the long-term (relative) cost of that decision is to be borne results in all communities emphasizing the short-term expedients, while requiring that people live in a place for a few years before they vote — or perhaps buy property, or otherwise commit themselves to the community — allows for real sustainable differences in priority (some people want lower taxes and less spending on education, even including the long term ramifications, while others want more) where people with different preferences can sort themselves as Tiebout described.
MIT students have a certain amount of flexibility to live in Boston or Somerville, even if we don't consider choosing a different school to be a real choice; on the other hand, MIT institutionally has much less such flexibility, and the students, faculty, and so on will be affected by the city's policies. It would be good to have that represented somehow, but on many issues, I can see the value to excluding the transients from the decision.