I don't think China is making that equation in any way. China has openly repeated that Ukraine and Taiwan issues should not be compared. Russia is a sovereign state, China is not going to exchange the right of selling weapons to Russia with the west selling weapon to Taiwan.The point is to equate China with Ukraine, two countries whose territorial integrity is being threatened. That presents the West with a choice to either condemn Taiwanese separatism or accept Chinese weapons sales to Russia. As it's clear that they'll pick Taiwan, China might be able to spin it as giving an excuse to supply Russia.
China does not need to spin anything for selling weapon to a sovereign state.
In principle it is true, but China only stated sovereignty of Ukraine without mentioning territory. Besides, so many countries' territorial boundaries have been changed since UN establishment, the very recent is Serbia. If that can not be reversed/respected, why should China give any effort for Ukraine who is in the enemy camp? The reality is that if your opponent is selective on rules, so should you, nothing to be ashamed of.China making a peace proposal that's based on anything else than the principle of territorial integrity would be highly damaging to Chinese credibility. Sovereignty and territorial integrity has been a foundation of Chinese foreign policy for decades
China makes a proposal but don't expect China would press Russia to give up anything. China isn't to pay her own political investment in Russia for the benefit of Ukraine who just robbed China not long ago.