This is a simple liquidity problem. SVB had the treasury bills and loan book to cover all the deposits. They just couldn’t access any of that money. The FDIC should take on the bills and loans, and pay out the cash now. They will collect the entire balance eventually and they have the benefit of time and I imagine they’re authorised to hold assets like this long-term (or do a cash swap with the fed, they have plenty…
They would never have been able to sell enough to not be able to cover their deposits - that’s when regulators stepped in.