Khashoggi was a long time Saudi intelligence operative who operated in Afghanistan during the Afghan Russian war, then was posted in the US embassy for several years as an intelligence officer, officially "advisor to the ambassador". He turned journalist and was very loyalist to the Saudi royalty. The ascension of the current monarch and his son turned him after power swapping that happened in Saudi, so he left and turned "activist". He held so much dirty laundry on the Saudi govt from his previous work that they saw him as a threat. I doubt Ali Soufan or any other Saudi dissidents are seen as such a threat as Khashoggi.