Your link says literally nothing about secession, despite my claim being about secession
Someone that doesn't consider themselves Chinese is seceding from China.
You don’t believe China has a right to self-defense
They do. Invading an island is as little self-defence as bombing Iran.
You hold the position that is aligned with Western imperialist goals (“Since when can you choose your neighbours?”)
'Since when can you choose your neighbours' has nothing to do with 'Western imperialist goals' but is a fact that affects all countries globally.
And then you pivot to Korea in a way that is so disingenuous
Except it isn't. The PRC/ROC split is the result of the Chinese Civil War, just as the NK/SK split is the result of the Korean Civil War. Both wars ended in a status quo where neither side controls the entirety, de facto resulting in two separate countries since decades.
So, if you negate the possibility of such an outcome in the Chinese question, you should negate this possibility in the Korean question and hence argue for South Korea, as the stronger part, to be entitled to force 'reunification' with the crippling North, which is rightfully theirs.