Americans in general are stubborn to a fault and full of ourselves internationally. It would be less altruism to save Taiwan and more "fuck China". The sanctions on Russia are predicted to make gasoline prices soar, especially on the West Coast, and it's anecdotal but the conversations I'm hearing are less polite versions of "fine, I'm willing to pay a little more at the pump to stick it to Putin". Although I'm not on the west coast I'd agree with the sentiment.

Then you have Republicans, right now they're deriding Biden for going soft on Putin and blaming him for this crisis (not sure how many are buying it outside of Trump's base, but that's the line). So going soft on a Chinese invasion of Taiwan would play right into that message. No way Biden could do it for that reason alone, let alone the myriad of other motivations.

It's not a "fuck China" thing. It would be a severe short-term tactical blunder to lose Taiwan, not even considering the moral perspective. Modern military cannot function without semiconductors. And yes, we could (and are starting to) move those facilities to the US, but that takes a lot of time to complete. Not only to complete, but to get up to speed and running efficiently. If Taiwan is lost, our enemies bolster their semiconductor supply, and we lose the majority of ours.