Who cares? China will buy as many as they want.
Aside from that - you seem to know very little about the UAE/Oman and others swapping/trading Iranian oil on a everyday basis.
China is way ahead on alternative energy - compared even to Europe. Therefore they can if needed, compensate even Iranian oil via Russia (Europe can't) or from whoever - certainly not from the USA, aside from their existing trade-deal with the USA that also involves US oil.
Furthermore China is able to widen it's CTL capacity easily - with only the US then whining about CO2 emissions.