There's a phrase we've all heard a lot of in the last few months: fiduciary duty. It gets trotted out every time some Silicon Valley CEO makes the pilgrimage to Trump Tower in Manhattan, or agrees to serve the new president as an adviser on this or that.

No matter how strongly a chief executive may believe Donald Trump is bad news -- a liar, a bigot, a menace to world peace -- he's still the president of United States, and anyone whose company does business here has a responsibility to shareholders, private investors, and employees to seek a cordial working relationship with his administration.

The benefits of winning Trump's favor are obvious. After Elon Musk joined Trump's Council of Economic Advisers, the White House indicated it will redirect NASA's appropriation budget toward commercial spaceflight vendors. That shift could boost the value of Musk's SpaceX by billions of dollars.

Then there are the risks of not playing nice. Trump has repeatedly shown he's willing to play God with companies' share prices, using his 3 a.m. tweets to ambush CEOs he thinks are insufficiently committed to Making America Great Again.

This rationale mostly held sway until a few days ago, when Trump's executive orders on immigration and refugees unleashed a wave of outrage that forced most prominent tech leaders to declare their disapproval, in tones ranging from tepid to Biblical. (The herd movement, it must be said, wasn't great for Silicon Valley's self image as a land of mavericks and freethinkers.)

Largely overlooked in the new atmosphere of righteousness is the question of whether the whole premise that smart business leaders must get as friendly with Trump as political considerations permit was mistaken to begin with. If there's one thing that both Trump lovers and Trump haters agree on, it's that he's an anomaly. In his presence, the usual rules don't apply.

Of course CEOs have a fiduciary duty. But in the case of Trump, that duty might be the opposite of what it normally is. If fiduciary responsibility normally compels CEOs to cozy up to the sitting administration, now it compels them to maintain a guarded distance.

Don't believe me? Look what happened this weekend with Uber. Like Musk, Uber CEO Travis Kalanick serves on Trump's economic advisory board. Explaining the relationship to employees, Kalanick invoked a version of the fiduciary duty defense: Uber has an obligation to further its mission. "We'll partner with anyone in the world as long they're about making transportation in cities better, creating job opportunities, making it easier to get around, getting pollution out of the air and traffic off the streets."

Kalanick's complaisance provided the gasoline of outrage when the ridesharing company appeared to subvert a taxi strike in New York City Saturday night. Never mind that the timeline suggests Uber didn't attempt to profiteer; a #deleteUber movement sprung up on Twitter, and rival Lyft capitalized by announcing a $1 million donation to the ACLU. As of Monday, notes mobile analyst Tero Kuittinen, Lyft had blown by Uber in new downloads.

You don't have to despise Trump to acknowledge that he's unpredictable, controversial, and mercurial. Nonpartisan betting markets think there's a high probability he won't make it through his term without getting impeached. Posing for a photo op with him presents a PR risk in a way it just hasn't with any previous president, Republican or Democrat. Of course prudent CEOs are going to be cautious about making an enemy of the president. They should be. But they should be at least as cautious about making an enemy of the people.