If only wealthy employees can buy the 2000 new housing units close to the big corporate campus, then that means those 2000 workers are moving out of housing that's farther away, lowering prices (or at least slowing price rise) in those farther suburbs.
So yeah, maybe the company janitor can't afford the $1.2M luxury apartment next to campus, but maybe he can afford a $600K house 15 miles away instead of living in his $400K house 30 miles away.