He was a journalist, but he was also working for the Washington Post in particular, and he was an US resident, and the details of this murder where particularly gruesome. No need for the jab about the media here.
I'm not saying that it wasn't horrific what happened to him, but the question was why was there so much focus on his case, and the reason is because the media loves to report on themselves over anything else.
Right now, the US is screaming about the veil right after recriminalizing abortion. Meanwhile:
Saudi woman given 34-year prison sentence for using Twitter
https://www.theguardian.com/world/2022/aug/16/saudi-woman-gi...
Saudi woman jailed for 45 years over social media use, says group
https://www.theguardian.com/world/2022/aug/30/saudi-woman-gi...
Saudi Arabia is imprisoning women while the rest of the world is not paying attention
https://theconversation.com/saudi-arabia-is-imprisoning-wome...
These stories get a little attention from the press ostensibly because they're about speech, but knowing modern journalism it's really because they are about Twitter. Women getting executed for infidelity? Not news.
I agree with your broader point that reports generally like to report on themselves when possible, but pretending the Khashoggi assassination (because that's what it was) isn't particularly newsworthy is kind of silly.