>>/7/
> The additional writings thing only works as an appendix to the GPL.
> Their new rule applies to their collaboration infrastructure and those have their own separate contract that govern them.

A court doesn't take as a given that the only terms affecting a Work is License.txt. They don't operate like a program. These extra rules are in writing and presented to anyone looking at the code (they're presented up front).

They explicitly state the opinion of the copyright holders to exclude paedophiles and anti-feminists.
A court could certainly see that as part of the licensing regime.

They are additional writings governing the disposition of the Work.
Yes they are a license(permission). Yes they are in addition to the GPL. Yes the copyright holders can do that.
(even if it would violate the copyright of the work from which some of the project was derived: it's up to the original copyright holder to enforce his original terms against the down-the-line licensee) (the california case challenging this hasn't made it through the courts yet (suggesting 3rd party benificiary standing (under a contract theory of copyright (where an actual good was purchased for sale))))

It is made clear that paedophiles and anti-feminists are NOT permitted to engage with the Linux Kernel, with Xonotic, with Darkplaces, with anything in the opensource world. That rule is actively enforced.

And that is underscored with Kitsune being summerly banned.
Yes this is a licensing change.
And yes it can go beyond "merely" being banned for "the community".
Xonotic and Darkplaces could go to court, should Kitsune continue development, and explain to the court that they do not want Kitsune to have access to their Works.
The Court can then read ALL the wrightings associated with the Work, and come to the conclusion that the no-pedophiles clause is binding. Just because it is not in License.txt is not dispositive.

Additionally: kitsune has no consideration vs Xonotic and Darkplaces: so whatever license he had: isn't worth anything. It can be revoked. And the court could note that it, constructively, has been.

Think of Constructive Eviction, and Constructive Dismissal.

Additionally, both in Xonotic's case, and in Darkplaces, some of the copyright holders evinced that they did not desire paedophiles (such as Kitsune in their mind) to have anything to do with what they were doing at all: and to not be allowed to be associated with their Works at all. That's a license revocation: once they voted on it and acted upon it.

Which they did.