There is nothing a priori that prevents an admin from watching a contentious article that is already under enforcement and stepping in when needed.  I probably did this a few times myself.  You can have situations where the participants don't realize how toxic behavior is to others who might want to contribute (or indeed, they might enjoy the toxic environment).  That said, if there is a concern that an admin is being too heavy-handed, it seems like the place to bring it up first is WP:AE so it can be reviewed by other admins who have experience in enforcement matters. Thatcher