No one is going to invade China. There is no country on Earth with the logistical capability to sustain a continental scale land war in China. As long as China is not the aggressor, then there is no moral basis for an invasion.
The US has not installed missiles in Taiwan so the last point is moot. Could this happen in the future? Yes, but so could peaceful reunification or the status quo. One can spend a lifetime arguing about hypothetical threats and contingencies, but until it happens we should not always assume the worst case scenario.