I feel like I'm missing something here. US doing that would have made them much stronger against China. I mean just imagine how much more robust the European economy would be if all the gas going to China was going right to Europe.
Though in typing that out I may have answered my own question. Is it really just because US wanted to European market to themselves? This seems incredibly short sighted.
In addition to what other comrades said, USA did not considered China a threat. I don't know why, maybe they fell to their own propaganda constantly predicting China's "imminent fall". You can see from the rapid development of events around 2018+ that they just woken up on that back then.
But i don't think it would changed anything. Russia allied with Europe is much more dangerous to the USA than Russia allied with China, because that first alliance would inevitably restrict USA influence to just Americas and Pacific, while that second one just means new Cold War.