No, they liquidated those positions at a loss because of outflows. They are actually short the cash.
What we don't know is did they liquidate the positions that were more valuable in order to take a smaller loss, or positions that were most underwater? I'm guessing it's the former, which would mean they were in even worse shape with the unsold securities.
1: https://www.nationalreview.com/2023/03/the-real-reason-silic...
Now that those assets are in the FDIC's hands, though, they can likely be unwound really slowly and without a ton of execution slippage, which would have otherwise happened if this were a firesale.