Not even that time information about a US Bioweapon meant to destroy grain crops was leaked? You would think they might have cut back more over that fiasco... Hah, who are we kidding, China seems just as likely to purposely do that to themselves at this point.
I just think it's odd that the largest cancelled wheat shipments is now and not at any point in the past, that there were plenty of reasons for China not to import grains previously.
China has historically relied on US imports for its food security. A lot of their foreign policy over the past 30 years has had to do with importing food while exporting manufactured goods back to the US (to put it extremely simply).
The biggest reason for the shift now is that Russia can (has to?) offer grain at a lower price with the sanctions going on, which is "free real estate" for China.
It's not that the can or are cancelling all imports of grain, just imports from the US.
But the risk of losing grains due to aforementioned bioweapon was there and they still didn't cancel shipments, which weakens the food security argument. When you explained it is an economic choice between equivalent goods then it all made sense, that was a solid point.