Between that tweet (completely bereft of detail) from SBF (who is now a confirmed fraud...), and the FTX bankruptcy filing, I think there's a simple explanation for it.
1. Only some of the silos/firms in the silos have been audited. The auditor, thus, has no idea if there are unrecorded liabilities (SBF didn't exactly keep notes about where the money was supposed to be) between different firms in the silo.
2. The WRS silo (FTX US, FTX US Derivatives, etc) has been audited by a real accounting firm. The auditor for the Dotcom Silo (FTX.com, other exchanges, etc) was Prager Metis[1], the "First-ever CPA firm to officialy open its Metaverse headquarters in the metaverse platform Decentraland." I have doubts that this one was a through GAAP audit.
3. There were no audits at all for the Alameda/Ventures silos.
4. Crypto crashed earlier this year, which probably wiped out most of the stupid investments FTX made. It's possible that they may been only half-a-billion-in-the-hole in 2021, as opposed to ten-billion-in-the-hole.
[2] “I don’t know anything about FTX,” said Jerry Eitel, the partner emeritus and chief metaverse officer at Prager Metis. “I’m retired,” Eitel added, before disconnecting on the phone. (Eitel is a one-time CoinDesk contributor.) The head of Prager Metis’ audit practice could not be reached for comment.
I completely agree that the audit, to the extent that there was one, must have been pretty crummy. But that they technically had one meant there wasn't a clear "this is an unaudited financial company" red flag.
They did pass a GAAP audit, unbelievably in retrospect: https://blockworks.co/news/ftx-joins-coinbase-kraken-with-us...