Hi,
In order for you to be able to moderate Facebook comments plugin you have to add a Facebook UID of an admin. I can do this for you. Also, you we may consider using other plugins that has more options or using the official Facebook plugin for WP.
As far as I know and checked on the API browser there is no way to scrape the IDs of the commentators like you can do on Facebook pages or groups.
I'm ready to discuss this project with you
Best,
Igor.