Restrict access to certain dashboard pages based on user id

I would just disable the editor entirely. It is a dangerous tool anyway. I compare it to working on an airplane while its flying. Edit wp-config.php to add:

define('DISALLOW_FILE_EDIT',true);

You can reverse that by re-editing your wp-config.php and uploading over FTP (or maybe you have direct file access), as you should be doing anyway, but no one will be able to get to the editor to mess around with things.