(TL;DR of the following points: Global Supply !=
Global Availability)
This analysis misses the real issue by focusing merely on global supply rather than the entire system. I'm also not sure of the accuracy of some estimates, that could be fog-of-war, but while the USDA is estimating 7M ton shortfall in exports, Ukraine exports about 24M tons annually [1] and has banned all exports of wheat & other food staples. [2] They've already shipped some grain this year, but the longer this conflict continues, the worse the problem will get.
Maybe that doesn't yet change the overall global supply picture too much, but the author is not taking into account three very important aspects of this
1) Countries that have imported significant portions of their grains from Ukraine will be hit extremely hard by this. It's not much comfort to a country like Egypt that imports a significant amount of its food, a lot of that from Ukraine & Russia, to say "Oh but the global supply is barely reduced!". Contracts & import logistics of this magnitude don't turn on a dime, and there are undoubtedly logistical issues that make Egypt import from its current suppliers rather than another major exporter like the US.
2) During times of great uncertainly, global supply becomes somewhat disconnected from $cost. In terms of food availability, especially in poorer countries or to poorer people in somewhat wealthier countries, it's really not relevant that global supply is up or down a few points when the current price of wheat futures is up 40%. Absent significant intervention (such as subsidies) lots of people are going to go hungry.
3) It's worth noting global logistics separate from #1 above. In normal times pivoting quickly in this way would be difficult. Right now? Global logistics are still an absolute mess. It looks like bottlenecks are marginally better in places like SoCal, but there are shortages of a) ships b) shipping containers c) warehouse space d) trucking/drivers e) probably more. This will not only further complicate shifting to different suppliers, but also drive the end-point $cost higher than just the increase for the grain itself.
[1] https://farmpolicynews.illinois.edu/2022/02/a-closer-look-at...
[2] https://time.com/6156160/ukraine-bans-wheat-exports/