What does China do if the US avoids the conflict and simply resorts to economic sanctions against China? What if the US is able to build an international coalition on sanctions? I feel like sanctions and global perception turning against China is a much bigger risk then US intervention!
Here is the better question, what difference would enacting sanctions be after a conflict over what is being done now?
The US is trying to disrupt the Chinese economy and outright trying to collapse Chinese-owned companies despite there being no open conflict between the two countries. American fortunes in China are basically resting on the rationality of Chinese leadership not to retaliate in kind.
Western perception is already against China (ie. Xinjiang situation, accusations of intellectual property theft, spying, etc.), so what is really different?
You could argue there would be harsher sanctions, but then the economic hardship will be difficult for either side to endure. Is Taiwan worth it?