I’m not sure why you brought up the CC license; unlicensed GitHub repos do not use that and, generally, it’s understood that CC licenses cover documentation only for the reasons you cited.
I think you and I fundamentally disagree about the point of FSF. Open source is not a vow of poverty, you’re right; copyleft damn near is. Open source is an umbrella that covers both open and copyleft licenses. For the average business that wants to keep closed source code, copyleft modules are poison. I’ve handled the compliance process for both SMB and enterprise companies. Unless you’re someone like Red Hat, copyleft is basically noncommercial. AGPL, SSPL, and BSL are joke licenses that also present the exact same problems as copyleft albeit much worse for businesses to pick up. If you couldn’t tell, I don’t like copyleft code because I don’t think it’s okay to place restrictions on code beyond the basic litigation coverage things like the Apache 2.0 offer.
As for what SN is doing, my read of that was the code would be AGPL moving forward. My understanding is that you don’t need contributor approval to apply it (depending on the original license; in the case of the unlicensed code they have full power) but you do need contributor approval to remove it. If you’re right and they’re going to drop it after applying it, they’re opening themselves up to litigation should someone choose to pursue it.
Edit: just looked at the repo; they replaced the root AGPL with the CC license instead of, say, linking the CC license for docs and leaving AGPL in place. The individual packages don’t have licenses and the root code (eg scripts) don’t have one either. Ignore what I said about SN; they did everything wrong and it’s stressful to look at.