Americans openly talk about intervening in Taiwan, while strongly against intervening in Ukraine. The only difference I see is Russia has a huge nuclear stockpile, and China doesn't. China needs a respectable nuclear arsenal, it's only thing US politicians fear and respect apparently.
I think American leaders are well aware of China's ability to use hypersonic nukes against the US... but then again, some American politicians think Chinese warships are made from Uyghur slave labor so I can't be totally sure.
That said, this discrepency between how they treat Ukraine and the ROC is for 2 reasons:
1. The difference in how blowhards talk when they're there vs when not there... and America is the biggest blowhard in the world.
When not there:
"Bro, you let him get away after he said that shit to you??!! If I was there, I would have mauled that guy; he would have wished he were dead. I'd shut his fat mouth in an instant! Ohh, I wish I were there!"
When actually there:
"Bro, why do we have to do this? We both have families, it's a Friday night, why don't we just shake hands and walk away? Look, bro, we'll both wake up tomorrow morning happy we didn't do anything crazy or stupid tonight."
2. Russia's still the guy on the subway with a bottle of liquor and a switchblade. Don't wanna mess with him; he's no danger to you as long as you stay away. China's the rich muscular guy in a suit who will take over your business, brainwash your kids, seduce your wife, and beat your ass too and he's coming for you so you might as well face him now before he decides it's time.