They are in fact planning to do just that - put more office space in that zone, which will create demand for housing in SF (the nearest major residential area) rather than adding housing. And in the past, they've blocked a proposal that would have added 70K residential units.
http://www.latimes.com/politics/la-pol-ca-small-city-control...
The attitude is essentially, "I've got mine, let's pull the ladder up after me and deny anyone else affordable housing."