Everyone learned this during the collapse of banks in the mid 2000s. Everyone knows that holding accounts at multiple banks is a way around it.
This isn't something that's specific to businesses either - it applies to individual accounts the same. They took a risk by holding more than 250k in a single account and a risk isn't a risk if there's no chance of failure.
I can't stress this enough, but markets do better when agents have skin in the game. Commercial survival of the fittest requires failure.