They can always stop developing or fork to a different license and all future work belongs under that license, but you can't back date licenses, so what exists is guaranteed Open Source. If you're super worried, you can create a fork and just keep it in sync.
But this is essentially true about any other OSS project so I wouldn't be concerned. As far as I'm aware, conda was never open sourced and had always distributed binaries.
[0] https://github.com/astral-sh/uv?tab=readme-ov-file#license
Because it uses PyPI I'm happy to use it as a package manager and dev tool. The worst that can happen is I have to switch back to pip etc. But I wouldn't use it as package runtime dependency. Use pyinstaller for that.
The use case for this kind of trick I think is developer utility scripts in repos. I wouldn't want to tie any of my personal utils to uv. If it needs dependencies I'll just make a package, which is dead easy now.
uv just uses pypi, so it would be just a question of changing from uv to pip, poetry or whatever, all packages would still be coming from the same place.
I peeked in uv's contributing guide and issues and didn't see any CLA. In PyTorch the CLA was mentioned at the top of the contributing guide.
Although, there should have been a community fork of the last FOSS version of Anaconda. That's what happened with Redis, and Redis uses a CLA: https://github.com/redis/redis/blob/unstable/CONTRIBUTING.md...
Don't ever sign a CLA, kids. Hell, only contribute to copyleft projects. We get paid too much to work for free.