First, Khashoggi is being used as a cudgel against President Trump’s foreign policy. The Trump administration has cultivated deep ties with Saudi strongman Mohammad bin Salman in a symbiotic relationship. The Saudis serve as the focal point in the Trump administration’s Gulf counter-jihadist alliance, as well as its Sunni Arab anti-Iran coalition. The United States provides bin Salman both military and political support, and credibility that he hopes will enable him to open Saudi Arabia to foreign capital to underwrite his modernization efforts and cement his rule on a more stable foundation.
Much of the establishment is seeking to force the Trump administration to ditch the Saudis — enemies of progressive Wilsonian foreign policy establishment darling Iran and its beloved fallen Iran Deal — thereby scuttling the Trump administration’s overall counter-jihadist, anti-Khomeinist Middle East policy. This policy is the polar opposite of the Obama administration’s, which the establishment of course largely supported.
Second, casting bin Salman as a murderous dictator feeds into one of the establishment’s favorite narratives, that Trump embraces authoritarians and harbors authoritarian tendencies himself. The counter of course is that foreign policy requires partnering at times with unsavory regimes that reject our values in order to advance our greater interests, and Trump understands this.