This was my thinking as well. Even the verbiage is similar to what China has said in the past about Taiwan, except now it is Russia saying it about Ukraine.
China is has a much weaker military and smaller nuke arsenal. Tangling directly with Russia is incredibly dangerous. China too, but less so.
China is estimated to have approximately 100 nuclear warheads and delivery systems that can reach the continental United States, anything over that would not make much sense anyway. Smaller is a relative term, in absolute terms this is a devastatingly powerful set of weapons.
China has a more powerful military than Russia at this point and vastly superior manufacturing and economic means to sustain it and push further. China's nuclear arsenal is merely smaller, but so what, nobody needs 10,000 nukes anyway. A thousand well-aimed nukes will do the job.
It makes sense. Helping the Ukrainian coup of 2014 doesn’t cost the US much but a direct war with Russia would be catastrophic.
You know how anti-vaxx trolls have certain key words and phrases they apparently can't stop themselves from using, which gives them away?
For their pro-Putler colleagues, one of those phrases is "Ukrainian coup of 2014".