A real weakness but quite misunderstood and exaggerated. It is true that China is quite vulnerable to an oil blockade. But there are a few things people miss.
1- Malacca isn't very important. It is used because of the infrastructure provided by Singapore and its closeness to the Asian mainland. There are many bodies of water there. In fact, the largest oil tankers already avoid Malacca because of its shallowness. The assets the US needs to blockade China are quite substantial in amount because of this. This means a lot fewer assets to deal with in China's periphery
2- It would have no effects on Chinese war making capability, heating and electricity production. China produces a lot of oil and heating is usually done using coal. Transportation would be hit. But that's about it.
3- Most people miss it but modern navies are not suited for either blockades or merchant escorts. They grew too small for that. Unless the US engages in unrestricted warfare against merchant marine I can't see how they could accomplish an effective blockade.
4- Blockading China equals blockading the entire world and a blanket blockade on SCS and the Persian gulf would break the global economy. It would have huge political costs for the USA.
5- Most US patrol assets, which would be spread thin because of the geography, would be vulnerable to Chinese surface groups and conventional subs. Yuan is not a coastal sub after all. Only American assets that are under aircraft carrier coverage would be safe.
You made a lot of great points.
However, there is one key factor to consider: Submarines.
Submarines, thanks to their stealthiness, can make direct observation and interdiction very challenging simply by using the water blanket as cover.
Which is why submarines are so effective at hunting convoys during both Atlantic Wars. This is also why the Soviet Navy envisioned that their nuclear attack submarines be sent to the North Atlantic to intercept any NATO reinforcement convoys coming from the US to Europe in case a land war between NATO and Warsaw Pact broke out on Europe.
It is a well known fact that the US and her allies have the best submarines suited for long-range operations, which is absolutely perfect for stopping oil and gas shipping between the Middle East and China.
By distributing those attack submarines in the Indian Ocean and Western Pacific Ocean, I believe they have sufficient capabilities of not just facing off with the PLAN, but also interdicting shippings heading towards China.
Of course such actions would have global-scale consequences, but it's not like you can expect the US and her allies to be reasonable at this point, when their combined nuclear arsenal are the largest or 2nd largest. Just look at how arrogant and ignorant they are since the start of the Russia-Ukraine war.
(This is in light of reports where nuclear-armed countries in the West, especially in the US, vowed to even nuke countries like India, Brazil and Indonesia if they are getting nuked, just because of the "If I'm going down, I would rather take everyone down with me than leave anyone standing. And I mean EVERYONE." mentality.)
Hence, I believe that submarines are the utmost threat towards the shipping lanes between China and the Middle East. This needs to be look after and effectively countered in case of war.