If anything, involving them in the 'rebuilding' process would cultivate a more realistic prospect of sectarian unity. Exiling them and forbidding them from getting involved in the political process will only radicalise them and their supporters into throwing their weight behind the Al Qaeda extremists. Maliki has done an appalling job of easing sectarian fears, if anything he's exacerbated it with his increasingly sectarian sentiments.
You also have to look at it from a pragmatic perspective. The most trained and decorated Iraqi military personnel served under Saddam. Getting rid of all of them and replacing them with a rag-tag group of recruits was never going to end well, as is proving to be the case now.
I disagree strongly on both accounts. Here is one of the Sunni candidates in the main Sunni party in the last elections (the first woman on the list) talking about Al-Maliki.
I can translate it for you if you don't speak Arabic. This whole sectarian isolation is no more than propaganda to justify what they wanted to do all along, ever since Saddam was overthrown. There is a deep sectarian division and mistrust in the country, the Sunnis will not accept a Shia PM and the Shia will not accept a Sunni PM. Al-Maliki has done many things to ensure all sects are treated equally. He even agreed to return most of the Baathists to their original positions to reassure them, which was a very big concession (kind of like the Nazis being returned to the German government in 1950). However, as I said, the sectarian division in the country is just too deep.
And by the way, Al-Jaafari, the Shia PM before Maliki, was also rejected by the Sunnis and they accused him too of all kind of things, and they eventually (practically) vetoed the idea of him running again for PM, which is why he was then replaced by Al-Maliki. So it's not really about Al-Maliki.
On the other hand, you're mis-interpreting what happened in Mosul. There was pretty much no fight in Mosul. The army generals withdrew before they even fought ISIL. It was pre-planned, and it wasn't the "young generals" who did it, it was the old "good" Baathist generals who did it. The problem the Iraqi army is facing now is not "experience". It's loyalty. And that's the reason why it was a mistake to return those "trained military personnel" from the Saddam era to sensitive positions imo.
Oh and by the way, those high ranked Baathist military personnel weren't dying of hunger. They were receiving pension. They were just kept away from the sensitive positions in the security forces because of their history, but they were returned later under pressure to their positions, and this is the result.
As for the military capabilities of the new army, I just want to remind you that the same army (minus most of those Baathist generals who were returned afterwards) fought Al-Mahdi militia in Basra in 2008 and they were highly effective and restored calm to the city in one week.. So they know how to fight.