Taipei considered sending 200,000 troops during the Korean War to be used as the spearhead for a reinvasion of the mainland. For a long time the Guomindang harbored plans of returning to the mainland, even if those plans were unrealistic.
At any rate, yes, it is a civil war. Taiwan is not a renegade province, it's the vestiage of the old mainland government that was defeated by the Communists. They lost, and headed a government in exile on Taiwan.
When we had our revolution, we didn't want to keep being English. The people on Taiwan and the people on the mainland both think of themselves as Zhongguoren, or Chinese. They both want to be part of China. They want to be separate from the Communists, but they don't want to stop being Chinese. Well, guess what. They are separate from the Communists, and they are Chinese.
In most circumstances, I'd say 'Screw the PRC' and back Taiwan. The fact of the matter is that we need China's help with North Korea first. After North Korea falls, I don't care much what Taiwan does to piss them off. I hope that they do.
But for Taiwan to start trouble before we've gotten what we want from China is not in our interests. They should know better then to put us in this position. That's the issue.
For the KMT leaders, this statement is true. However, most of the population did not migrate to Taiwan at the end of the Civil War. The native population is in power and is trying to change the national language from Mandarin to Taiwanese. They don't want to be called Chinese, but Taiwanese. They want a different national flag and passport. They have no desire for "reunification".
Chiang kai-shek is dead. If the free people of Taiwan declare in a referendum that they want independence that is their right, unless you disagree with the spirit and letter of the Declaration of Indepedence.