The poisoning of dissidents was done with biological and nuclear weapons to underscore the point that Putin has them and is willing to use them flagrantly.

Also that Russia has recently used chemical weapons against civilians. If China was actually worried about this subject (and not deflecting from Covid scrutiny), they'd be watching Russia's actions in Ukraine very closely. Attacking nuclear reactors and now talking up chemical weapons indicates Russia is aiming for a false flag pretext where they blame Ukraine for Russia's misdeeds. Like accusing Ukraine of shelling their own refuges, when artillery is Russia's core strength.