Do transplants from other metros really move to Staten Island though?
It's probably not very likely, conservatives who move to the New York area for work are probably more likely to relocate to the suburbs. The small minority of transplants though who do care enough about politics to want to have neighbors with the same political views are likely to be true believers and probably bolster the area's preexisting character. I think that ProgressiveModerate made a good point in that self-sorting among native New Yorkers is a much larger factor. Staten Island has long been a white flight magnet and this is even reflected in the local accent (which also persists in Long Island, pronounced "Longuylin") being closer to the now dying WWC New York Irish that was more prevalent decades ago in Brooklyn and Queens but is now largely extinct there.