Here's MY "realpolitik" on the subject:
Kashoggi was an "internal issue".
The Saudis settled it as a matter of "family business" as does the Mafia right here.
If the murder has stirred up the waves, I expect the Saudis will "settle it amongst themselves".
Nothing for us to do to intervene, or for that matter, to even understand what's goin' on...