I think the defense leaned on the part where the owner of the service basically allowed him to keep it, plus cooperation; if the judge rules him innocent (e.g. while he exploited a bug, the then-owner did not press charges and rewarded him), he might get the BTC back, but this time cleared of any crimes. Meaning he can cash in and walk free.

Well, relatively free, his face and name are known and if he is exonerated, everyone will know he's a multi-billionaire and the life of himself and others are in danger.