If true, all the more reason to question our alliance with the Saudis
Not at all. Back during WWII, Roosevelt supported the USSR, Uncle Joe and his entire Gulag Archipelago justice system, because National Socialist Germany was considered more of a risk.
Similarly here, the Mullahs of Iran are the enemy of peace, they are seeking thermonuclear weapons and the Kingdom of Saudi Arabia is their enemy.
BTW, the Saudis investigated the death of Khashoggi and he apparently got into a fist fight with some other fellows in the consulate. Those things happen, not as if the fate of Khashoggi is really America's concern.
I feel the pain for Mr. Khashoggi's family, but it would be stupid to wage war against Saudi Arabia or cut off relations with a country that seems to be coming around over this.