That's a very optimistic scenario. But I'm not that optimistic for ASEAN. After years of observing what communities of nations did during Covid, the Ukraine War, and the Israel-Gaza War. As an inhabitant of SEA myself, my gut feeling is that if and when the Straits of Malacca is blockaded, ASEAN will be very divided about what to do. Singapore, I suspect will be paralyzed by indecisiveness and confusion as it'll be split between the US and China. It'll be doing alot of diplomatic work and posturing, but it won't do anything too serious to anger either side. Malaysia and Brunei are just hopeless cowards. They will hide away from any fight. Myanmar will be too busy in its civil war and will stay out. The Philippines is the US's pet in SEA, so it'll support the US. So maybe, just maybe, Indonesia, Thailand, Vietnam, and the various Indo-China nations might actually have the guts to do something and join forces with China to re-open the SOM. Because these nations are the current growth engines for ASEAN, and have a future to fight for.
If the Straits of Malacca (and presumably the other straits in Indonesia) are completely blockaded, it would cause a severe economic crisis in most ASEAN states. This is far more serious than your examples of "Covid, the Ukraine War, and the Israel-Gaza War"
So what happens to all the neutral shipping from the Middle Eastern to ASEAN? Or the traffic from Africa and India to ASEAN?