Apologies for replying rather late.
I think this argument is certainly valid but it is important to examine all options, and not make assumptions. The US is physically weak but whether it will ever be capable of realizing it, and what it would actually do in a crisis situation, may be another question.
Again, to be clear, there is nothing wrong with your argument, I would just like to emphasize how it is important to consider all possibilities.
Expanding the nuclear deterrent should be China's number one priority now. Without it, the US could feel pressured to intervene in Taiwan even if it knows it can't win, and may feel a war with China is feasible, if not desirable.
Take for example the instance of Japan just prior to US entry into WWII. Your take feels eerily similar to the way the US calculated Japan's potential actions and vice versa*. I'll outline the similarities in an identical list one by one.
- The US likely assumed the Japanese government and military was aware of the economic disparity between the two. It indeed was, numerous reports had been prepared for Japanese leadership detailing the economic comparison between the US and Japan, as has been revealed by recent research. Even the fanatical IJA was aware that Japan didn't stand a chance.
- Assumed implication: They believed that Japan would make the smart decision and give up their aims in China in favor of keeping Korea and their other Pacific possessions intact and avoiding war.
- Actual implication: The US failed to underestimate Japan's warped view of the world- i.e. just because the US saw the reality didn't mean Japan did too- and its fanatical determination to become the dominant power in Asia.
- Japan continued negotiations with the US all the way up until bombs fell on Pearl Harbor. It seemingly expressed a willingness to find a diplomatic solution to the tension.
- Assumed implication: Japan's desire for war was not absolute, it could be negotiated with, and despite the poor progress of the negotiations and the increasing hostility in relations between the two, war was not imminent and some degree of peace remained likely.
- Actual implication: The US failed to recognize that Japan's relations with the US did not exist in a vacuum. Japan was under the assumption that the the world order was changing; the USSR was on the verge of collapse and the US was dilapidated as a result of the Great Depression. As a result Japan was far more willing to cross the river Styx and attack the Western colonial powers than the US had thought.
- The Japanese government saw the US as being decadent, corrupt, and too interested in maintaining its own economic prosperity to engage in a prolonged war. Likewise, the whole of the US establishment saw Japan as a backwards nation, run by copy cats and corrupt generals. Neither side believed each other had much fighting power or will to fight.
- Assumed implication: There was little to no chance of either side engaging in a major conflict because neither had the guts to go all the way.
- Actual implication: Both sides gave into their biases and severely underestimated each other. Japan, shaped by its warped world view, was all in on going to war with the Western powers, while the US was fully prepared to give up peace to occupy half the world despite the huge economic and human cost.
- Japan considered the US reaction to the war in Europe to be weak, seeing it as a sign of isolationism holding sway over the country. The lack of response to the USS Panay incident and the seemingly divided nature of the country, focused on recovering from the Great Depression instead of foreign issues, led it to assume that if a decisive campaign could be fought, the US could be brought to its heels.
- Assumed implication: The US was too weak to put up a fight in Asia. It's response to German aggression in the decade prior and its domestic issues (the New Deal continued to be divisive and the Republicans called Roosevelt a dictator bent on provoking war).
- Actual implication: Despite all of these issues, the US retained great strength and as a result of Japan miscalculating the American response to what was supposed to be a demoralizing, decisive strike at Pearl Harbor, America was fully enraged and ready to go to total war.
The possibility that the US government could lash out and launch a full scale intervention over Taiwan should still be seriously considered despite the events of the past weeks. After Ukraine, the US could feel pressured to intervene to stop what it sees as a return to use of military power to achieve policy goals similar to the 1930s once and for all. Despite knowing it lacks conventional superiority it may over rely on it's nuclear arsenal and underestimate China's resolve to take the island. The idea that Taiwan is nothing more than a rally round the flag cause for another corrupt and greedy authoritarian government remains strong in US thinking, i.e. the whole of the US establishment treats China and Taiwan like Iraq and Kuwait. Not the talking heads in the newspapers and online commentary websites, the people who actually hold power and make decisions. We see a similar situation with Russia and Ukraine. In contrast, the US of 60 years ago understood the USSR was not merely an aggressive dictatorship but actually sought to achieve security goals in Cuba and came to a compromise with the latter. It should not be assumed the same can be counted on in the US, not only now but onwards throughout the century.
The danger of a US-China war may have increased rather than been shown to be low. Taiwan isn't merely a South Vietnam to the American empire, it is more like West Berlin. A fall of Taiwan without US intervention would signal the end of American power in the region and be enough of a shock to force the pro-US establishment out of Japan and potentially even South Korea sooner or later. Even if Biden (or his administration, to be more accurate) refuses to accept that, the political and economic establishment will not have it. If it would have it, and was more interested in maintaining its economic fortunes instead of political goals as some have claimed, none of this tension and salami slicing over Taiwan would exist in the first place, and therefore I don't think they have such interests at heart and remain bent on maintaining American dominance in Asia no matter the cost. But instead of being suicidal or being somehow soullessly capable of accepting the economic devastation of a US-China war, they likely don't even understand the consequences of what might happen, just as Japan had no idea what it was actually getting itself into during WWII.
*Again, there is nothing wrong with that argument, even it it seems like I am trying to invalidate it. I simply think the "peaceful reunification is inevitable" opinion that has been going around here is just as dangerous as the calls for war, and that all options need to be considered.
