(Speaking for myself, not ECC.)
You might have missed that it depends on the orchard crate and so is relying on the license exception of that crate for “Zcash projects published by ECC”.
This is indeed, by my interpretation, not open-source (it conflicts with clause 8 of the Open Source Definition).
It is a bug that the README files of projects that rely on this exception don’t say that they’re relying on it. I’m on holiday but someone should fix that.
Edit: I filed Projects that rely on BOSL exceptions should say that they do · Issue #5931 · zcash/zcash · GitHub . This really should be filed for all of the repos depending on orchard, though.
Later edit: filed
- Projects that rely on BOSL exceptions should say that they do · Issue #576 · zcash/librustzcash · GitHub
- Projects that rely on BOSL exceptions should say that they do · Issue #36 · ZcashFoundation/zcash_script · GitHub
- Projects that rely on BOSL exceptions should say that they do · Issue #4716 · ZcashFoundation/zebra · GitHub