Ok, I guess something different happened.
I'll admit I didn't click through to prove that I could. I just took the site's word for it. There does seem to be some confusion here. When first claiming one could create groups I hadn't noticed the big headline:
The address in question is invalid. In fact it is in Bouncing status (but not NC) per shalstest's Pending Members list. I expected it to be both.
So I'm not sure how this address escaped NC status, unless there was some automatic response from my email service that "smelled" like a reply to the confirmation request.