I think the old owners of the suddenly active Yahoo group still have ownership rights. What I did with a couple of my old Yahoo groups (that had been moved to io in 2018) was remove all the members except for myself and one moderator. Or the Groups.io transfer agent. Why not just delete the group? Sentimentality? I came close to deleting a couple of them but...I just couldn't do it. LOL
Actually, I believe in never say never. Who knows what may be in store down the road.
tommy0421
Tommy Meehan