That would honestly be the best option for the Taiwanese (other than magically fighting off an invasion with minimal civilian casualties of course). Taiwan only exists because the US stepped in front of Communist China in the 1950s. It wasn't even democratic at the time, but became democratic with US support. But the US essentially birthed a democratic nation on land disputed by a massive neighbor for its own geopolitical goals. In an alternate universe without the US intervention, would the Taiwanese people of that universe even have a distinct identity to agonize over? If the US raised generations of democracy supporters in harms way, doesn't it have a responsibility to take them out of harms way if it cannot defend Taiwan in the future? The Taiwanese may not have their island, but they'll still have their democracy and lives in the country that is arguably singlehandedly responsible for their existence.