Hi, I’ve just had the same issue. I managed to hide the publish meta box with a quick hack. If you go into the plugin editor, select Lock Pages then click on the lock-pages.php file. You need to find this bit of code:
remove_meta_box( 'slugdiv', 'page', 'normal' );
Add just below it
remove_meta_box( 'submitdiv', 'page', 'side' );
Then the publish meta box is taken away too. Hope this helps!
