Earlier quoted context omitted.
I think the Librem5 will have a CC-by-SA 4.0 license, aka copyleft, so it'd have to be open source.
That's a weird statement. Why would they use a CC license, rather than a software license like the GPL?
The argument for using the GPL when creating copyleft software is that most copyleft software uses the GPL and you want everything to have a compatible license, that’s not really the case for hardware.