Freddie Mac’s former chief executive is fighting hard to prevent the Office of Federal Housing Enterprise Oversight from keeping about $53 million in salary and benefits, but the legal contest may help further solidify the regulator’s power over the GSEs. “It would go a long way toward helping them fulfill their mandate as a regulator [if OFHEO prevails],” said one legal expert on the GSEs. “I think [the current statute] is pretty broad regarding