A few days before that tweet: A person familiar with the matter said that the Department of Justice and the Securities and Exchange Commission (SEC) were examining FTX to determine whether any criminal activity or securities offenses were committed.

https://www.theguardian.com/technology/2022/nov/10/ftx-crypt...

The good thing about saying that something is "not inconceivable" is that then you don't have to provide any evidence for it.