We were somewhat better placed to open it up, we had separated various parts more completely, hadn't put in the full billing engine, and had no third party code or other things that we were distributing that might be an issue.
But... one of the things nirvdrum didn't touch upon was that we just hadn't designed it to be a single-server, single-customer install.
We designed it as a platform, and made assumptions along the way. I didn't mind opening the embarrassing code (everyone's shit smells), but the people who were asking all seemed to want a single, well-documented install... and we were having to walk away and go get a day job.
We did choose to open it in the end, and you'll find our work here: https://github.com/microcosm-cc/
But I only know of a few people who have actually installed it to date (and struggled, because it's not well documented). All of the effort to open-source it just found another set of tyre kickers.
Sigh. It's tough. Just letting go. And it's definitely made tougher by wrangling with these questions and trying to do the right thing without investing so much at a time when you're exhausted, broke and likely quite down about things.