Top right hand corner there is a padlock. Click on that, then options for who can contact me, click on that and go from there. It did only let me have 2 options regarding friends requests, everyone or friends of friends. If he refuses friends immediately and changes to this setting, then it should work out as essentially no one will be able to request him, if that makes sense. I'm sure there used to be a total block, he might also want to change the settings (in the same bit)