If you are talking about his Vox interview over Twitter, he claimed every step was rational (he did not claim legal) in isolation.
But the details look different. He admits that FTX said they never invest the deposits. He then claims he loaned that money to Alameda who invested the deposits. That seems like an important pair of details. Those two things help combine with other facts to build the legal case. He also admits he didn't really lend them out to Alameda, probably because it evaded the margin limits.
Look, he's not running around saying "I ran a giant fraud". He may even think he did nothing wrong. But he is agreeing to some of the pieces prosecutors need to prove. Given FTX's bad records, just confirming basic facts is good for the prosecution.
But the details look different. He admits that FTX said they never invest the deposits. He then claims he loaned that money to Alameda who invested the deposits. That seems like an important pair of details. Those two things help combine with other facts to build the legal case. He also admits he didn't really lend them out to Alameda, probably because it evaded the margin limits.
Look, he's not running around saying "I ran a giant fraud". He may even think he did nothing wrong. But he is agreeing to some of the pieces prosecutors need to prove. Given FTX's bad records, just confirming basic facts is good for the prosecution.