Putin actually did a good job laying out Russia’s justifications for the invasion. If you listen to his speeches, the reasons are obvious.Beyond hardware, the justification of starting a war is extremely important. It impacts both international opinion and domestic support. With hindsight, Russia's biggest mistake in the current war was failing to frame the war properly and being widely seen as the aggressor. It directly affected Russia's international standing and in large part caused their shortage of manpower.
By framing every move to blockade TW as a response to American provocation, China could potentially put TW under complete blockade without giving the US any causus belli.
Once that happens, TW would be on a timer, and the US would have a very difficult time trying to avoid being seen as the aggressor if they tried to break China's blockade.
Make no mistake, if that happens, it will mean direct war between US and China. However, the US may very well find itself bereft of support both at home and abroad should that occur.
It didn’t help Russia none because it can’t control the narrative. Entire situation is made worse by Russia’s lackluster performance on the battlefield.
The same problem faces China. It will be framed as the aggressor no matter the justifications. It can’t control the narrative.