What I said was that it depends on the circumstances. Do you understand?? I would evaluate all of these things on a case by case basis. I would probably think some of them are ok, and others are not ok. That's different from saying "that all ok". Ok?
For example: Russia certainly has a legitimate grievance against Tbilisi regarding the border/bandits issue. So I might (might) indeed be ok with a Russia "build up effort and attack" against Georgia on those grounds. It would depend on the circumstances involved. (In particular it would depend on how confident I was that a Russian attack against Georgia would lead to a better situation than currently - and frankly I am skeptical.)
On the other hand: a claim by China that Taiwan is a "threat" to China, and an invasion of Taiwan on that basis, would probably be dismissed by me out of hand as absurd.
Some cases are different from other cases. I do not endorse a general rule "all preemptive attacks ok" or "all preemptive attacks not ok". NO GENERAL RULE. Do you understand???
Why for each it may seem as reason of life and death, regardless US opinion...
That may be true. It doesn't change anything I said. If China really thinks invading Taiwan is a matter of life and death for them, I would most likely simply disagree. What is your point?
so soon back to geopolitics of 1800s.
What do you mean "back"? Geopolitics has always been like this.