Tenant advocates and many of his own renters regard Laurence Gluck as the scourge of subsidized middle-class housing. He has bought more than a dozen New York City complexes since 2004 and removed rent ceilings from thousands of apartments. He borrowed $250m to buy and renovate the storied Riverton Houses in Harlem, pocketed tens of millions in profit and then lost the buildings in foreclosure earlier this month, leaving them an early casualty of the speculative real estate boom. But city and federal housing officials looking to rescue a troubled development in Crown Heights, Brooklyn, have begun viewing Gluck in a different light: as its possible savior.