As others suggest, why stay attached to Manjaro at all? Instead of forking, what about expending that energy on a rising distro without such reputational damage?
CachyOS is very close “in spirit” if they want to develop modified/custom packages, but there are plenty Arch downstream distros with less toxic communities.
They could even fork some other project and make the changes they like. It’d be a saner base than Manjaro at this point.