> possible collusion in the murder of US national Jamal Khashoggi
Not central to the point, but Kashoggi was not a US national. He was a US-resident Saudi citizen. It's possible to be a US national but not a citizen, but Kashoggi wasn't one: https://www.immihelp.com/immigration/us-national.html
Quibbling over status is an interesting fallout of the same right-wing nationalist rhetoric. You're right though. He was a Saudi citizen, US resident on an O Visa with US citizen children on his way to a green card[1].
> Should we not care about his murder as much then?
Actually, the correction was so that people wouldn't continue making the mistake, not because his citizenship status is a critical point. The error is a distraction from the main point that is avoidable in the future.
Not central to the point, but Kashoggi was not a US national. He was a US-resident Saudi citizen. It's possible to be a US national but not a citizen, but Kashoggi wasn't one: https://www.immihelp.com/immigration/us-national.html