I think everything is flexible depending on situation - if it suits the current US narrative and situation they would support us - if not ..... just like the UK in WW2.
I am sure back then if they could have they would have, but just did not have sufficent resources to do so, so in stepped USA.
I think relations between Chiffley and Churchill may have not been the best either given their world viewpoints.
On a side note The East India Company was not the real start start to the Empire - I'd say they were the logical succesors to the Caribbean sugar trade - that was the real gold mine that kicked off the British mercantile / naval trade empire.
That was also possibly the root cause of
a) S7W (French vs British part) and thus also the AWI.
b) The wealth driving the Industrial Revolution - all that money sloshing around looking for something to do.
c) The search for new markets / opportunities thus also led to the EIC, which of course overtook the West Indies.
Empire by accidental design is my take. Too incompetent to have a grand scheme, just looking for a main chance - then used by some to extend their influence dressed up as bringing "civilisation" to the benighted savages.
Whereas the Chinese seem to have taken a proper Marxist 5 year plan approach. However very easy to fall into the Orientalist trap. I imagine like with the Birtish / US Empires it is a mixture of things - both plans and personal empire building. Possibly with just a little more organisation
Better start learning Mandarin and investing in umbrellas and face masks.