I think you know the answer too.
IMO, the DT doesn't like the timing of this. It's happening over the next 12 months, a critical time for dealing with the depositions, civil suits, etc. I think they are afraid Casey will mess up if she has to appear in court and potentially take an oath to tell the truth. If she lies it might jeopardize her probation, but if she were to be truthful at any point it would hurt her position in any of these upcoming cases. That's the only reason I can think of for so many attorneys being so dead-set against an order of probation.