You're missing the subtlety here. There is no legal precedent requiring corporate fiduciary duty to focus solely on shareholders. In practice, however, it's a reference to the Realpolitik of being ousted by a Board, enabled to do so by arguing a fiduciary responsibility to shareholders.
If it wasn't, the ghoulish masquerade of Corporate Social Responsibility wouldn't be a thing - it in itself a response to Milton Friedman's 1970 article “The Social Responsibility of Business Is to Increase Its Profits” which argued that corporate executives are agents of shareholders and should focus solely on maximizing returns, not social responsibility.
> While it is certainly true that a central objective of for-profit corporations is to make money, modern corporate law does not require for-profit corporations to pursue profit at the expense of everything else, and many do not do so. For-profit corporations, with ownership approval, support a wide variety of charitable causes, and it is not at all uncommon for such corporations to further humanitarian and other altruistic objectives. Many examples come readily to mind. So long as its owners agree, a for-profit corporation may take costly pollution-control and energy-conservation measures that go beyond what the law requires. A for-profit corporation that operates facilities in other countries may exceed the requirements of local law regarding working conditions and benefits.
——
The best I understand it, what this ultimately means is that, yes; if the shareholders hold a vote to say "you need to focus on profits over X thing you're doing now/planning to do", you have to do that, but absent a specific shareholder mandate, you are not in any way obligated to seek profit over all else.
Ford lost this case because he overtly admitted that he wasn't pursuing profit and because he was deliberately trying to prevent minority shareholders from getting money to start up a rival car company.
If he had just made some vague claim that what he was doing was in the long-term interest of shareholders, he probably would have gotten away with it.
But we see how some companies cough cough Apple cough throw massive hissy fits and tries to find the most minuscule opening on the law