I second this. I think more than the moderation part, a private group where only a limited number of users will be found is much better for those who are pretty active so that they can make use of the bonuses and promotions when they are announced if they are on a first-come, first-served basis because if the group is crowded, you will barely get the opportunity to get a bonus because they will already be claimed and if the group is public, bonus abusers will always be present in it.

The moderation can be managed if they hire a moderator that will take care of the chat at most of the times, and when the human moderator isn't present, the bot can do the work by filtering words and links and banning those who are spamming the chat or trying to scam others by providing phishing links, etc.