So according to the Bluesky thread, the ship was captained by a Russian citizen. One has to wonder whether this was done with the approval of the Chinese government, or whether the ship was just chosen by opportunity (which seems possible given that China is the second most common merchant flag). Or whether implicating China was even an explicit goal.

For an analogy, it seems like a scrappy preteen throwing around his big brother's name, knowing that if he gets into trouble, big brother will intervene...

(i.e. the European countries might be more wary about boarding a Chinese ship compared to a Russian ship, because escalating against China is scarier...).

I think China stands to gain from escalation of the war so its possible they approved. It makes Russia weaker and more dependant on them, distracts the US from the Pacific, and weakens Europe in many ways.

Similar to both Russia and China gaining from war and disruption in the Middle East.

There are many possibilities here.

Russian captain, how does the ownership history of the ship look? Could be some sanction evading ship that was owned by Russian interests anyhow.

China did not want the war in Ukraine, which has created serious problems for them including for Belt and Road. So behing closed doors China must be passed off but Russia is important to them and they can't let them collapse.

Of course Putin knows this hence him somewhat taking the p.

I doubt China will be happy, if Russia staged chinese support. But rumors have it, that the North Korean troop support for the war in Ukraine also came out of the blue for China, so Putin might make a risky gamble here, but I doubt he dares it. If China would seriously drop support for Russia, they would be srewed.