I found that you cannot simply right click on the public folder in Outlook and designate a moderator, as for some reason the setting is not retained.
You can however do it from the Exchange powershell.
It is not possible to assign a group, however you can add multiple user with comma delimited syntax, like this:
[PS] C:\Windows\system32>Set-MailPublicFolder "Public Folder Name" -ModerationEnabled $True -ModeratedBy "User One", "User Two", "User Three"
Now all posts to the designated public folder result in a moderation email being sent to the designated multiple recipients.