I seriously doubt that is what happened. The commissioner has the ability to overturn the ruling herself. The fact that she did not tells us that she either agrees with the ruling, is indifferent or, well, lets just say has an alterior motive to keeping BIEL down.
The Senator could have ordered her to send the appeal to the IG, or she could have contacted the IG herself.
No way the commissioner goes to the IG and basically says, 'Hey, this decision came out of my organization, but we want you to investigate it to see if any wrongdoing has taken place'.
The request came from outside the FDA, likely from the Senator.