Without reading the article, I can give you the answer immediately. SVB failed because they were bankrupt. This is what it is called when your liabilities are in excess of your assets.
They were not insolvent. They had a liquidity crisis. This has been stated hundreds of times in depth now.
For regulatory purposes, the SVB was permitted to ignore those losses in bonds that it intended to hold to maturity. Accounting doesn't change reality, though. If the SVB's assets are actually worth more than their liabilities to depositors in any economically meaningful sense, then why do you think the FDIC was unable to find a buyer?