I'm still suspicious one factory shutdown could cause this much of a disruption.
How many BF factories are there in the US? It would kind of scare me if we're relying on only a handful for the whole country. Would make it an easy mark for someone wanting to mess with the US. A couple of bombs or even just contaminants here and there and you could have a major disruption and panic like what we're seeing right now.
I think our entire economy is that way. It would not surprise me at all if there is one or two relevant factories. In fact, the market usually results in a monopoly or at most duopoly, especially for high volume, low margin goods. We no longer have breweries in every town. Instead there's a few giant ones and we truck things across the country. The market has evolved to do that because the consumer has prioritized the lowest price.
Think of it this way, if a factory can shut down and NOT cause a supply disruption, that means they were producing more formula than could be consumed. Why would they produce more formula than needed, which nobody would buy? Who would pay for that over production? Nobody. So it's inevitable that any shutdown will cause a disruption. The market solution is a lean supply chain so that prices on the shelf rise quickly and other plants can start up or ramp up quickly to fill the supply gap. If supply is still too inelastic, presumably a contracts and futures market will arise to help (and I'm sure there already are such markets operating in the formula supply chain). There's no other market solution. If it's sufficiently important, potentially the government could buy a certain percentage of the output and destroy it. That's close to what we do with certain agriculture markets and defense markets. Any other government solution would probably make things worse by raising costs without actually improving supply flexibility.