Private/Hidden Admin Only Taxonomy

Hi guys

My site is: http://thethemeparkdirectory.com/

And I’m wondering if it is possible to se thet wordpress back end so that certain taxonomy options are admin only. Here’s exactly what I would like to do

I currently have my site set up so that there is a custom post type “dir-item” which anyone with Editor privileges can add to/edit.

This custom post type has both Location and Categories taxonomies. The categories taxonomy is split into the following 4 categories.

Theme Parks
Water Parks
Indoor Entertainment Centre
& Under Construction.

Any editor can currently add items to or edit anything in these 4 categories.

What I would like to do is add a 5th (and eventually 6th) option under Categories for Airports (and eventually train stations) which only admins can add/edit.

So when creating a new Item an Admin can place it in the airports category and it then won’t show up on the editors items page.

I’m not sure this is even possible but any thoughts or help would be greatly appreciated.

(I think there is a 2nd way around this by creating a custom post type which editors don’t have permissions for but I don’t have the Java knowledge to include those locations in the front page google map)

Thanks
Dave