I really disagree with you on matters of practical import, as well as philosophically. I'll address only the former here. China is on the verge of starvation continually. There's a whole lot of degraded formerly arable land China is trying to rehab, but that isn't yet rehabbed. China is in process of creating the ability to produce food on that land, and is actually doing amazingly well, for instance, by raising salmon in the desert of Xinjiang - an astounding accomplishment.
Oz and Brazil cannot make up the shortfall from the US. A couple years ago the scouring of food China could grasp was illustrated by the massive disappearance of donkeys from Africa, because China was butchering them. China purchased Smithfield Pork to mitigate it's food supply problem. These things don't substantially address the issue China has, however, and China won't address that issue because it is dependent on preventing the actual solution, which is decentralization.
Aquaponics can resolve the issue, and a whole bunch of other problems that come along with food supply fragility, regarding quality control. When supplies are short, quality is sacrificed, and issues notorious in China involving all kinds of taints are worsening. The CCP needs the population to be dependent on it for it's survival, and thus cannot solve it's food supply problem by decentralizing food production with aquaponics. This makes the CCP dependent on US food supplies for it's survival.
While you claim China's exports are a negligible fraction of it's total, that's very misleading, because China is on the edge, deliberately, because you have to be at that bleeding edge to develop as rapidly as China has been, and intends to continue to be. The reality is that sudden drop in exports is utterly existential for the CCP, and it will come to the table or resort to war. War is the last thing China needs, and it is not ready. The only option for the CCP is to find a way to alter it's bleeding edge market development to reduce tariffs on US products, and quickly. How to do this without losing face is the only problem that hasn't been solved, but I suspect it will be solved pretty soon, and the tariff war will end.