That first group can be browsed even if you're not a member of Chess.com. The second group can be browsed only if you're a member of the group. I see no reason to hide content from non-members, but it's obviously up to the group's admin to decide. I also found another, older chess960 group, currently inactive. I know from experience that it's tough to maintain momentum in a discussion group, but it might come back to life in the future.
One of the big advantages of a discussion group is being able to discover resources that others post about the group's common interest. I found one thread in the forum of the first group listed above (Chess960 RandomChess) titled On the Opening in Chess960 (FRC). It points to an article on Chessville.com, On the Opening in Fischer Random Chess by Robert T. Tuohey. His premise is,
The FRC player is required to analyze the particular starting array he finds before him based solely upon general principles. Very strangely, considering the countless articles written on FRC, this, the most basic problem posed by this variant -- i.e., How do I go about analyzing an FRC opening position? -- has all but been ignored! With this in mind, then, I’d like to offer the following basic method.
That's an excellent subject for discussion and, after the Chess.com thread runs its course, I might return to it on this blog. On top of that, I hadn't been aware that Chessville had an interest in chess960, so I'll tackle that subject in my next post.