they're limiting the height of whatever tower gets built to 280'. I think that was also the cap to the Westchester Pavilion redevelopment. The people of White Plains need to think taller, though this article suggests there might have been some lobbying on the part of the Ritz Carlton to limit the height of such a nearby development.
Former White Plains Mall Cited for Zoning Change
here's the source for the redevelopment at 60 S. Broadway being limited to 280'