I agree. The defense will win this, not because it is improper, but because Casey is just plain lucky.
Even if it were to be ruled that she does have to serve this probation there will probably be some special provision just for Casey, that she does not have to report in person "for her personal safety."
Probation served in jail is ridiculous. Probation is supposed to be a test that the person must pass in order to retain their freedom. If it is instead of jail time, the minute they screw up they must serve the jail time. If it is upon release from jail, it is intended as a transition period for the person to show that they can live in society and follow society's rules. There's no way probation served while incarcerated is either a test or a transition.
What will probably happen is that for Casey, the rules will once again be bent completely out of shape. Luck usually runs out eventually, but I will not be surprised if for Casey that doesn't happen anytime soon.