As often with proprietary source code, it may include some third-party code or libraries that they have no right to redistribute, for example. To "free" a repos

As often with proprietary source code, it may include some third-party code or libraries that they have no right to redistribute, for example. To "free" a repository, you must first audit the code for 3rd-party code and check the legal status of this code, and you may need to replace it with a free replacement, and find a license compatible with all the code. That may represent a significant effort, with associated costs...