[Financier Kirk Kerkorian's hefty investment in General Motors may make him an ally of the CEO instead of a dreaded corporate raider, as the company pushes for unpleasant changes such as forcing unionized employees to pay for more of their medical care and breaking down internal fiefdoms.] It's external ammunition for the changes GM has to make but that others have resisted, ... The Kerkorian bid could be a very good thing for the company.