I can accept that reasoning. The Russian involvement is business, not politics.
Mother Russia is still sick and needs income. She has no exports worth a damn. Rocket technology and perhaps critical components are of quality and salable.
It can be argued that many of Putin’s actions including flying bombers close to various countries and the involvement in Syria are actually sales efforts to promote his only export products worth a damn.
Oh and by the way, the discussion here of a declaration of war and such fail to mention that the United Nations was engaged in battle with North Korea and the situation is under a cease fire that has existed for 60 years or so. I think ceremonial talks are presently ongoing at Panmunjom but don’t know for sure
Russia and China are allies in a general sense but they do have different priorities and needs.