Here is a comment from Reddit. Seems like it is really only about the build toolchain. It’s reasonable and clears the confusion I think.
kmoore134 wrote:
Bottom line is, the open source bits of TrueNAS will remain open source. (They are GPLv3 after all). The build system is another matter. It’s currently changing fairly radically internally now around for a variety of reasons, some of which are related our signing infrastructure for secure boot, etc. Meaning we’d be stuck maintaining two separate builders potentially to assemble an ISO file, one for community builds, one for the official builds. That isn’t super tenable for us in the long term.
That said, the repo is still there. Folks can fork / maintain it. All the open source bits can be built if the community so desires this functionality. But I’d wager 99% of the folks commenting on this thread have never done a build from source before, nor would ever want to? Its a lot of work to do and maintain. Especially since the biggest consumers tend to be overseas forks which contribute nothing back to the overall development effort to create TrueNAS, thats a lot of effort for us to shoulder the burden on for no real gain.