The majority of the Iraqi Army in 2003 no longer wanted to be under Saddam - They would have in no way, shape or form tried to restore the old regime.
You just don't have an accurate understanding of what the ground situation was early on in this war.
Those several units that were very loyal to Saddam (and his sons) would of course been disbanded (and many arrested...and this did happen).
However, we also through out a vast number of semi to decent-trained people in both the Army as well as local Gov't officials (and caused ill will among these people). Only to then ask them back less then 3,6 or 8 months later.
I find it quite comical how many are so brave and not concerned with creating unnecessary ill-will....when your as$es aren't ever on the line to deal with the deadly ramifications of those actions.
When tough decisions have to be made and through those decisions some ill-will comes (along with the added danger) so be it - That is part of being a soldier. However, when it is clear (on the ground) that some of the added danger / ill will can be avoided....it most certainly should be...(especially so if those pushing the other direction are doing it from the safety of 10,000 miles away! - Or holed up in some "Green-Zone").
Read the rest of my posts on here (before I will go further).