The CLA is sort of a red herring in the case of permissively licensed software though. It becomes relevant for the SSPL case, where Redis don't want to be bound

The CLA is sort of a red herring in the case of permissively licensed software though. It becomes relevant for the SSPL case, where Redis don't want to be bound by the same rules as others. Like since Rust is MIT licensed, you could make a closed source fork of Rust. The trademark guidelines would prevent you calling it Rust or anything too close, but you could describe it as Rust(TM) compatible and any of the other legally permitted uses of other people's trademarks.