well, I won’t share any details out of respect for their deletion.
Suffice it to say that they had problems with the moderation of Risa and evidently wanted to create a community with the kind of moderation they want. As TenForward has multiple moderators, Stamets was clearly not alone in this.
I think if you were to read the comments in the linked welcome message for TenForward, as well as the welcome message itself, you’ll get the picture.