Thomas Biskup of ADoM said that he'd not publicly release the ADoM code for two reasons. First, people would trawl it for the secrets (discovery is a big part of the ADoM experience). Secondly, he was embarrassed about the state of his code and didn't want to let people see...
He did do a re-release recently that I funded on $kickstarter_analogue, but I haven't had a chance to play with it yet (and it's been a while...)
There are numerous public prereleases available and I'm playing the most current one right now (the barebones ascii version). It's still the ADOM I knew, but now with extra dungeons, stuff to do and a variety of fixes for bugs and scummy exploits.
Yeah, I understand they wouldn't be convinced to release the source, but that's why I am thinking about a middle ground, to have someone volunteer to help organize it, while still keeping the code private.
Though I guess there's the question of trust... would have to be someone they knew very well.
I see it as a double edged sword. It's good we get DF, but at the same time, DF itself is a huge mess.