Option one: The Treasury secretary was speaking to an audience of one. Mnuchin is under enormous pressure from President Donald Trump, who is upset about the market sell-off and mad at the current Federal Reserve chairman, Jay Powell. The press release was perhaps an attempt to show Trump that Mnuchin was doing something, anything, to talk the markets back into stability.
It makes some kind of squint-and-see-it sense. Mnuchin used Twitter earlier in the weekend to reassure the markets that Trump was not going to fire Powell, who has continued to tap up interest rates as the economy continues to grow at a decent pace. Mnuchin wrote that Trump told him he “totally” disagrees with Fed policy, calling it “an absolute terrible thing to do at this time.” But he said that Trump had informed him, “I never suggested firing Chairman Jay Powell, nor do I believe I have the right to do so.” The readout might be a further effort to keep Trump calm by showing him that everything is fine and his Treasury is taking action.
The problem with this explanation is that it means Mnuchin risked roiling financial markets to placate his boss (which of course would only further anger his boss).