SA-Russian relations have been strained by Syria, but they've actually improved substantially since mid/late 2016. MBS was in Moscow talking military issues in May 2016. And in September SA signed an agreement with Russia to limit oil production, widely seen as a major win for SA and OPEC more broadly. At the time, MBS explicitly told the Washington Post (of all papers) that he intended to coordinate with Russia to encourage them to move their regional focus from Tehran to Riyadh.

In 2017, they followed that up with a massive three-part contract selling Russian weapons to SA, committing Saudi money to energy investments in Russia, and bringing Russian petrochemical plants into SA. Later in 2017, the Saudis started pressuring the US to drop sanctions on Russia over Ukraine.

Saudi/Russian relations aren't perfect, but they've improved substantially. And more importantly, the improvement is heavily tied to MBS personally and his new direction for the country.

Meanwhile, Turkey is heavily pushing this story via the Istanbul consulate angle, in what's generally described as an attempt to destabilize a regional competitor and personally undermine MBS and his new direction. (Turkey likewise has strained-but-improving relations with Russia thanks to the work of its new strongman leader.) Depending on who you listen to, some of the extended Saud family is also advocating for this to become a crisis in order to oust MBS and return SA to its older positions.

So I can't really see what Russia gains from striking out at SA now, especially via a line that does less to weaken the country and more to weaken a specific leader who's been more friendly to Russia than his predecessors. This looks like a regional spat between two states Russia has been courting, plus an internal fight on which Russia sides heavily with MBS.