I was referring to changing the cache time on the module not the page.  If a module gives edit permission to registered users then the page will show the mode bar for view/edit.

I don't know why the code above would hide the control panel for your host account.  It clearly only hides it for users that do not have edit permissions on the page.

There is one other option, but I'm not sure when it was added. Go to Admin > Site Settings, and look for  + Advanced Settings + Usability Settings : Control Panel Visibility

Set that to Page Editors instead of Module Editors.  It does the same thing as the code above if you have a version with that option.