I received a response from Dario when I sent a message to the general Smart Live address referring them to Universal4's earlier post, which contained some questions that had not been addressed by them (especially whether Casino City's experience of not having to rejoin is an exception or whether it is the case for everyone). Here is the information I received:

In response to the issues raised in the post:

The quota clause only applies from November the first, we have already sent an internal communication to all the existing affiliates a couple of weeks ago.

Also, the existing affiliates don’t need to rejoin, all the commissions generated during September and October has been paid now.
Based on this it sounds like if they'd referred to Rejoining in earlier communication that it must've been a bad choice of words meant to be about starting the advertising again rather than actually going through another sign-up process.

If there are any affiliates who haven't been paid what is owed to you, let me know. If their note about having processed everything is not accurate I want to make sure to follow up with them about it (there aren't any cases of this that I'm aware of).