Currently, my understanding is that this is a federal investigation, not an MLB investigation. Kinda out of MLBs hands. Not to say they don’t have influence, but they aren’t necessarily the final say.
From what I have read and heard, the federal investigation is into the illegal bookie that Mizuhara made the bets through and neither he or Ohtani are part of the criminal investigation.
Assuming Mizuhara actually stole the money, I guess he could end up in a criminal investigation if Ohtani presses charges.
Apparently MLB is waiting to see what happens with the Feds investigation before they decide what they will do. If I understand what was said correctly, MLB is unlikely to take any action unless it looks like Mizuhara and/or Ohtani bet on baseball.