I disagree with this on a number of levels. Ideologically, I think this is very much China's fight. In The Narrative(tm), Ukraine is an exemplary democracy and bastion of civilization standing against the Asiatic horde. Not only is it disgustingly racist, it's a complete fabrication. Ukraine's government makes Russia's look squeaky clean and it's been perpetrating crimes against humanity with abandon in the Donbass for the last eight years. No matter how false and morally repugnant the narrative is, it's the prevailing narrative in the West - which means the "exemplary democracy" must fall, and China must be seen to have a hand in its fall. This will have a powerful demoralizing effect on the enemy.
Let's say some miracle occurs and Ukraine "wins" (however one defines that). The West will be galvanized and emboldened. It will see that if it stands united it can still shape the world in its favour and will look to continue its crusade. Who's the next target of that crusade, do you think? People develop gambling addictions by winning, not losing; that's why the West can't be allowed to win.
The idea of supplying Russia with arms in support of its operations in Ukraine, places China and the US/Europe as fighting a proxy war in that theater.
If there was low to minimal risk of facing economic and geopolitical blowback in other domains -- specifically, China and US/Europe undergoing a sudden and painful economic/industrial/technological divorcing from each other similar to what Russia has experienced -- then the possibility of China assisting Russia might be more palatable.
However, I think the risk of a sudden economic/industrial/technological separation is too great and events are too fluid for China to consider the idea of supporting lethal arms to Russia to be worth the costs.
Economic/industrial/technological separation
will be painful for China as well as the west -- however for China, I suspect there are only certain things for which it is willing to bear that pain for.
The most likely one, is in event of a Taiwan conflict.
Taiwan's political status, as the overriding primary core interest of China, is naturally going to worth whatever pain or complications it may entail.
Is supporting Russia in Ukraine worth pulling out the pin in that particular grenade at this stage?
On a strategic level, let's imagine that China is waging a war in the Indo-Pacific to establish its predominance. How do you want Russia to think about this? Would you prefer that they think "China stood by us during our trying time, so we'll stand with them now" or "This is an Asian war. Why should Russia bruise itself over it?" This is a great opportunity to deepen the bonds between Russia and China, and those bonds will be needed in the years and decades to come.
In such a scenario, I expect Russia to also pursue its own strategic interests to the limit of their own strategic power, regardless of whether China provided them with military assistance in Ukraine on this occasion.
I don't think anyone in the Chinese government would be opposed to strengthen and deepen bonds between Russia and China.
But doing so by providing military support and arms to Russia at this moment in time, is not the only option to deepen said bonds in the short, medium or long term, and the high potential costs of providing said arms and military support may not be worth the benefits.
China has finite geopolitical and geoeconomic capacity to expend -- is providing military support and arms to Russia right now, really the best use of it?
All this isn't to say that China should not provide geopolitical and geoeconomic and technological support to Russia in a general manner. However, providing military arms or explicit military support, is something else entirely.
