The Confederates were allowed to secede or not? That was the question. Not who fired the first shot. History is full of false flag operations and misunderstandings. The Marco Polo Bridge Incident marks the point of the start of the Second Sino-Japanese War. If Japan was not intending to conquer China, that incident would have been a minor issue, but it was used to justify a full-scale war with China. The same with the Fort Sumter shooting - it's just one bloody excuse. Ditto the Gulf of Tonkin incident and the Vietnam War.
It's not up to Taiwan to agree or not. Taiwan has an even bigger fertility problem than on the mainland. Its barracks are emptying out. It just doesn't have enough men to defend the island in the future.
Also, more and more sectors of Taiwan's economy have been lost to the mainland. Semiconductors is next. And no, China is not going to invade Taiwan to seize the TSMC factories, contrary to popular Western opinion. All China needs to do is wait, until Taiwan's economy goes down the drain, because it will, due to Taiwan's very low fertility rate and ageing population.