THE DISAPPEARANCE and reported murder of Saudi journalist Jamal Khashoggi has prompted a justified wave of outrage and revulsion in Congress, the media and parts of the business community. Twenty-two senators from both parties have triggered a legal provision mandating an investigation by the Trump administration of whether human rights crimes were committed when Mr. Khashoggi entered the Saudi Consulate in Istanbul on Oct. 2; if so, those found responsible could be subject to U.S. sanctions. Legislators who have already been working to block further arms sales to the Saudi military, such as Sen. Chris Murphy (D-Conn.), say they now may have the votes.

Defections are meanwhile piling up among scheduled participants in a major investment conference planned for later this month in Riyadh. The New York Times, CNN, the Financial Times and Bloomberg News have pulled out as media sponsors, along with editors and executives from the Economist, CNBC and the Los Angeles Times. The chief executives of Viacom and Uber have canceled their appearances, along with investor Steve Case. Meanwhile, four board members of the planned NEOM business zone — a pet project of Crown Prince Mohammed bin Salman — have said they will step aside until questions are answered about Mr. Khashoggi’s disappearance. The Harbour Group, one of a number of lobbying firms working for the Saudi government, canceled its contract.

Several Wall Street executives, including Jamie Dimon of JPMorgan Chase and Stephen Schwarzman of the Blackstone Group, have not yet changed their plans to attend the conference, even though its host, the crown prince, is credibly suspected of ordering the capture or killing of Mr. Khashoggi, who had been living in Washington and writing regularly for The Post. That looks like poor judgment: Do they really want to be photographed next to a tyrant with fresh blood on his hands?

The real outliers, however, are President Trump and other senior officials in his administration, who continue to play down a horrific and virtually unprecedented crime — the alleged murder of a distinguished journalist in one of his own country’s consulates — and excuse Saudi Arabia’s failure to offer credible answers to their requests for information.

Mr. Trump responded to queries about the Khashoggi case on Thursday by calling it “a terrible thing” — but also by underlining that Mr. Khashoggi is not an American citizen (he is a legal resident with two U.S. citizen children) and by calling relations with Saudi Arabia “excellent.” The president harped on what he claims are $110 billion in pending Saudi arms purchases — deals The Post’s fact checker has described as “fanciful and unlikely to come to fruition.”

On Friday, Treasury Secretary Steven Mnuchin said he was still “planning on going at this point” to the conference, adding, “If more information comes out and changes, we can look at that.” That is the opposite of the appropriate position, which would be to suspend official U.S. participation unless and until Saudi authorities provide satisfactory answers. As they did before Mr. Khashoggi’s disappearance, Mr. Trump and his aides are sending the message that they will tolerate even the most reckless and unlawful adventures by the crown prince, provided he buys U.S. weapons. It’s hard to imagine a more irresponsible and amoral stance.